Welcome to the top tier, Collin Sexton.

There was a conventional wisdom leading into this basketball season said there were five players who are currently playing at American colleges as well as overseas were worth tanking for. In some sort of order, these players were Arizona's DeAndre Ayton, Duke's Marvin Bagley, Missouri's Michael Porter Jr., Texas' Mo Bamba and the Slovenian star Luka Doncic, who is playing professionally for Real Madrid in Spain. That top tier was clear, as was the single defining characteristic of the 2018 draft: It won't be nearly as deep as the 2017 NBA Draft, but the top of this draft will be absolutely loaded. It's possible that each of those five might have been the No. 1 overall pick if they had been in the 2017 draft.

Well, it's time to make that a top tier of six.

Alabama's Collin Sexton has been an absolute revelation in the first month of the season for Avery Johnson's team. Sexton is averaging 20.8 points, 3.5 assists and four rebounds. His most noteworthy game was a bizarre one, when he dropped 40 points on Minnesota the Saturday after Thanksgiving -- the final 19 points coming in the last 10 minutes of the game, when Alabama only had three players on the floor. (Alabama's entire bench had been ejected during a fracas. Later, another player fouled out, and another player left with an injury, leaving the Crimson Tide with only three available players.) It was a loss, and a bizarre anomaly of a game, but seeing Sexton confidently dribble and shoot into double-teams or triple-teams was the type of national statement players aren't usually able to make on the collegiate stage until March.

And the statement was this: Collin Sexton is ready for his moment.

So put Sexton's name into that top tier. I don't see an enormous amount of separation between any of these players, to be honest. I suppose you could say that the top four in this mock draft -- Bagley, Doncic, Ayton and Porter -- all have higher ceilings than Bamba (a massive defensive force with an uncertain offensive game) and Sexton (a fast and athletic point guard in the Eric Bledsoe mold). But all six of these dudes are absolutely great, and reason enough to make Chicago Bulls fans and Atlanta Hawks fans and Dallas Mavericks fans excited for the future.

Here's the latest mock draft with draft order set by the most recent NBA season projected win totals from Sportsline.

Reid Forgrave's Mock Draft
Marvin Bagley III, PF, Duke
He's nearly 7 feet tall, strong and an elite athlete -- and more important, it seems like the game comes so darn easy to him. He's averaging 22 points and 11 rebounds for Duke, and yet you get the sense that the Marvin Bagley we see in December is only scratching the surface of the Marvin Bagley we'll see in March. And that Marvin Bagley will be only scratching the surface of the Marvin Bagley we'll see in the NBA next year, and that Marvin Bagley ... you get the point. He can run the floor. He has one of the most incredible second jumps you'll ever see, as in Andrew Wiggins-like. He can shoot it. He has an insane work ethic and an irrepressible motor. And he's only going to get better, folks. Is he Kevin Garnett or Chris Bosh or James Worthy? The answer, perhaps, might simply be, "Yes."
Luka Doncic, SG, Slovenia
At 18 years old, Doncic is making a huge impact in the top Spanish league, where he's playing against grown men and averaging 16.9 points, 5.9 rebounds and 4.4 assists for Liga ACB's best team, Real Madrid. That's in a league where the top scorer is currently averaging 18.6 points. It's no surprise Doncic is excelling against older, bigger players, because mental maturity is a hallmark of his game. While he's not a ridiculous athlete like Bagley or a physical specimen like Ayton, he might have the top basketball instincts in this draft.
DeAndre Ayton, C, Arizona
Some players are tall. Some players are strong. Some players are so impossibly tall, so incredibly strong and wide-shouldered that one's eyes immediately focus on them the moment they step into a gym. The 7-foot-1 Ayton is the Bahamian David Robinson, a unicorn who is blessed with size and a variety of skills all around the court. On defense he's an intimidating presence despite, so far, middling results. On offense he can score from all three levels. Yes, his focus wanes at times. But when Ayton is focused and in his element, he's absolutely dominant. In the end, I expect the top pick to come down to a decision between Bagley and Ayton.
Michael Porter Jr., SF, Missouri
The biggest bummer of the first month of college basketball was Porter's back injury, which sent him into a surgery that might sideline him for the entire collegiate season. Back injuries in near-seven-footers are worrisome, which is the reason -- the only reason, really -- Porter should no longer be considered in contention for the No. 1 pick. And that's only because the three people ahead of him feel like such locks as NBA players. But Porter's game is exquisite. Imagine if you could take the collegiate Jayson Tatum and make him a little bit better at everything: a little bit taller, a little bit bigger, a little bit better shooter and a little bit better athlete. If the back is 100 percent going forward, Porter has one of the highest ceilings in this draft, if not the highest ceiling of them all.
Collin Sexton, PG, Alabama
Sexton is a lightning-quick, John Wall-ish point guard who loves to get to the bucket and can really shoot it from deep. One season under 16-year NBA veteran point guard Avery Johnson will only help the occasionally mistake-prone Sexton become an even smarter player. His defensive potential and ridiculous motor are both strengths. His game is one of the most exciting in college hoops.

From Brooklyn

Mo Bamba, C, Texas
The Rudy Gobert of Harlem. Bamba grew up in Harlem as a basketball prodigy, someone whose absurd size and length as well as defensive instincts call to mind the Utah Jazz's potential Defensive Player of the Year. While the offensive game is far behind the defensive game, Bamba is still averaging 10 points and 10 rebounds for Texas, and he's at least showing some confidence in putting up 3-pointers, even if he's not making them in games ... yet.

From Los Angeles Lakers

Kevin Knox, SF, Kentucky
Not much flash to his game, but Knox is all sorts of solid on both ends of the court. He can shoot it from the mid-range and from 3-point range, can score in the post and in transition. He's quick for such a big guy, and he's big for such a quick guy, which portends for great versatility at the next level. He's the type of player who can have a quiet 20-point, 10-rebound game.
Lonnie Walker, SG, Miami (Fla.)
The kid's game has swag. (Just like his wild haircut, which Miami teammates have dubbed "The Pineapple.") Walker hasn't seen the minutes yet that you would expect, partially because he missed a chunk of the offseason due to a knee injury and partly because he's surrounded by tons of veteran talent in Miami. But all you have to do is see him on the court and you can tell: The young man belongs. He has a high degree of swag and confidence to his game, a pretty jumper and a body that is long, lean and built. He's a 6-4 shooting guard with a 6-10 wingspan who can attack the rim or shoot from deep.
Jaren Jackson Jr., PF, Michigan State
I would be loathe to turn my top tier of six into a top tier of seven, and I don't expect to do that between now and the draft, unless someone emerges out of nowhere. But if my top tier does expand, it's likely that Jackson will be that seventh player. There are flashes of unicorn in Jackson's game, an elite shot blocker (nearly three per game) and a very good rebounder who also takes, and makes, 3-pointers. The potential is sky-high here, especially in an NBA that values this type of versatile big man.
Robert Williams III, PF/C, Texas A&M
Williams would have been a lottery pick after his freshman year. He'll be a lottery pick after his sophomore year, too -- and could easily go several picks higher than this. There aren't many players who are this big, this long, this strong and with this level of elite athletic abilities. He's one of the best rebounders and shot blockers in college basketball. Will he become an NBA star? I don't think so. Does he have a very high floor on what he can become as a winning player for a winning team? Absolutely.
Trevon Duval, PG, Duke
Will the Hornets re-sign Kemba Walker to a big-time contract after next season, when his current bargain deal is up? I don't know, but if they don't, it's not too soon to start grooming a replacement. Duval's game is flashy -- sometimes too flashy, as he likes to style himself a New York City-type guard -- and he can turn the ball over too much. But the flip side of that coin is that Duval is an explosive creator, for himself and for others. His defensive potential is very high. The only thing missing from his offensive game is a reliable jump shot, as evidenced by his 16.7 percent shooting from 3-point range and 62.5 percent shooting from the line. But he's the type who will put in the work.
Mikal Bridges, SF, Villanova
Is there a closer Paul George approximation in college basketball than Mikal Bridges? Bridges is the rare fourth-year college athlete (he redshirted his first year at Villanova) who looks like a lock to be a lottery pick. He's a national player of the year candidate, a player who excels at both ends of the court, with absurd athleticism and 3-point shooting that has improved every season and at this point should be considered elite (51 percent on 3-pointers nine games into this season). Bridges is a rare find: a high-ceiling player who can contribute to a winning NBA team immediately. Another testament to Jay Wright's player development.
Miles Bridges, SF, Michigan State
The biggest surprise of the offseason was Bridges' decision to stay at Michigan State. Even his coach, Tom Izzo, pushed him to go to the NBA, especially knowing that the top tier of the 2018 draft will be tougher to crack into than the top tier of the 2017 draft. But Bridges decided to come back for one more year of the college experience, and to try and lead this ridiculously talented Michigan State team to a national title. Yes, he's a tweener, a 6-6 combo forward. But do we really care so much about that in an increasingly positionless NBA, especially from a player as strong and freakishly athletic as Bridges? I know I don't. There's not a thing that Bridges can't do on the basketball court: Rebound, block shots, shoot it from deep and make creative shots from the mid-range, and, most of all, dunk, dunk, dunk. An NBA star? Doubt it. But Bridges will fill up a stat sheet and inject excitement.
Wendell Carter, PF/C, Duke
Not a flashy player, but solid in that same way as an Al Horford. He can do it all on the court, a strong, mobile big man who can shoot it, rebound, block shots and play smart, team basketball. He has a very mature game -- and a very mature mindset -- for an 18-year-old.
Hamidou Diallo, SG, Kentucky
Diallo, who joined Kentucky at midseason last year and redshirted for a semester, is an incredible runner and jumper (perhaps the best in this draft class) who is learning how to be a basketball player. He has elite potential as a defender and as a rebounding guard, but his Achilles heel is a big one: He can't really shoot. He knows that's his weakness, and has been his singular focus since he arrived in Lexington. If he had a consistent 3-point shot, Diallo would be near that highest elite tier in this draft.
Kris Wilkes, SF, UCLA
Wilkes was one of the more explosive, eye-popping athletes at the U19 tryouts last summer in Colorado Springs, and his all-around potential has translated during his freshman year at UCLA. Wilkes is a bit skinny, but he has the type of work ethic that ought to help his body improve in years to come. Wilkes has a pretty shot, too, and does a lot of the intangible things on the court. He has a chance to become a very solid NBA player.

From Miami

Gary Trent Jr., SG, Duke
A couple of his Duke teammates told me that Trent was a "bulldog." This feels like an accurate description of the son of former NBA player Gary Trent. Another good description: "lights-out shooter." His stats are middling this year for a stacked Duke team, but he has the potential to be an elite NBA shooter.

From Minnesota

Brandon McCoy, C, UNLV
The other defining characteristic of this draft, aside from the big-time talent in that top tier, is that it has a bevy of big men. Big men are all through this draft, from sure things like Ayton and Bagley to riskier propositions with huge upside, like McCoy. He is a big, broad center who can do all the things you want from a traditional center -- block shots, rebound, score in the post -- and is attempting to develop range on his shot as well as a more mature offensive skill set. If he develops his offensive game, that could turn the still-raw McCoy into a steal at this point in the draft.
Trae Young, PG, Oklahoma
There's as much Steph Curry in Oklahoma's freshman point guard as there is in any player in college basketball. He's short and slight, and he lacks elite explosiveness, but he absolutely has the ball on a string and can change speeds with the best of them. He also has an amazing basketball IQ. I suppose there's a big part of Steph's game missing here -- namely, elite-level 3-point shooting -- but Young's offensive creativity is remarkable. He's not going to maintain his ridiculous first month, where he averaged close to 30 points and 10 assists, but who would?
Bruce Brown, SG, Miami
Find me a closer approximation to Russell Westbrook in college basketball. (You can't.) Sure, Brown is no Westbrook clone, and he's no future MVP, but his on-court swagger, his athleticism, his versatility and his scoring ability remind you of the OKC star. Brown is an excellent perimeter defender and can rebound from the guard position.
Jarred Vanderbilt, SF, Kentucky
Vanderbilt has the look, the size and the motor. But you don't have to look deep to find the biggest flaw in Vanderbilt's game, namely, his abysmal shooting stats. We haven't seen Vanderbilt play for Kentucky yet after he injured his foot in a preseason practice, and given the cautious timetable, we might not see him at all. He hasn't even practiced with the team since his injury. The draft-day ceiling on Vanderbilt might be much higher than this -- perhaps somewhere in the lottery -- but the floor could be lower if these injury concerns continue.

From Oklahoma City

Grayson Allen, SG, Duke
J.J. Redick would have been the perfect offseason acquisition for the Wolves this past season. How about running it back and selecting a hated white shooting guard from Duke who can really light it up from 3-point range? Allen's college career has been tainted (I would say unfairly) by his unfortunate tripping incidents and emotional outbursts. But the fact is, he's an incredibly hard worker, a good locker room presence and most of all he's a winner.
Chimezie Metu, PF, USC
Metu is long and athletic, a player who has always had the size and the measurables to become an NBA player but has, in his three seasons at USC, learned to take a much smarter approach to basketball. He'll need to continue to improve his outside shooting if he wants to optimize his NBA potential, but there's still a place in the league for the high-energy above-the-rim athlete that he is today.
Mitchell Robinson, C, IMG Academy
Robinson could have been a lottery pick if he had made the right decisions in where to attend college. As it stands now, a bungled situation at Western Kentucky has Robinson sitting out the season to train for the NBA Draft. I can't imagine that situation won't raise red flags in NBA front offices. But red flags will not be raised at Robinson's physical profile and uncanny shot-blocking abilities. He's a legit 7-footer with a 7-4 wingspan, and is blessed with incredible athleticism and the instincts of a great shot-blocker. Offensively, Robinson is very much a work in progress -- that's an understatement -- but there's loads of potential to build on here.
Rui Hachimura, SF, Gonzaga
Hachimura was dominant this past summer at the FIBA U19 World Championships, where he averaged 20.6 points and 11 rebounds for Japan. He is big and strong and athletic, someone who plays hard and attacks the basket but needs to add more finesse to his game.

From Toronto

Austin Wiley, C, Auburn
It's a shame college basketball fans might not get to see Wiley play this season for Bruce Pearl's Auburn team, as he is being held out of play in the wake of the FBI investigation. Wiley is a formidable presence down low, and averaged a double-double for the USA U19 team that won a bronze medal at the FIBA World Championships in Egypt this summer.
Anfernee Simons, SG, IMG Academy
Simons, who is playing a fifth season of high school ball at IMG Academy and who turns 19 in June, would be able to satisfy the NBA's draft eligibility requirements despite not playing a collegiate game. Simons is a wonderful scorer at all three levels, but most impressively as a 3-point shooter. It's entirely possible that this lights-out shooter could go significantly higher than here.

From Houston

Allonzo Trier, SG, Arizona
An elite scorer -- but what else? Trier could use a lot more unselfishness to his game, because an NBA team isn't going to draft him here to be The Guy. He needs to learn how to become a role player, which is what he would be in the NBA -- someone who could provide a scoring spark off the bench.
Shake Milton, PG/SG, SMU
If you like long, lean combo guards (Milton is 6-6 with a 7-foot wingspan, elite size for an NBA guard), Milton is your guy. He's a very good shooter who has become better and better as a floor general. Best of all is Milton's ability to meld to what his team needs to be. He's not the type of player who needs to get his in order to feel like he's making a contribution.
Jalen Brunson, PG, Villanova
Please tell me about how Brunson's lack of athleticism and elite size will prevent him from becoming a solid NBA player. I'll tell you about how there's not a smarter player in college basketball. Brunson is one of the most efficient and creative shot-makers there is, from 3-point range, in the mid-range and at the rim. He pushes the ball, and he has great pace to his game, a la one of his basketball idols, Chris Paul. And like the best point guards, Brunson makes everyone around him better. He's the heart and soul of this Villanova team. Look past the typical measurables and you'll see a player who is filled with more intangibles than anyone in this draft.