There is less than three months between now and the 2021 NBA Draft, which means that with the college season in the rearview and the NBA's regular-season schedule winding down later this month, teams are launching full-speed ahead into draft prep. And while we still have several weeks until the deadline for underclassmen to declare (May 30), the class on the whole is already taking shape and a clear picture about how this year's crop may look by draft night is beginning to emerge. It calls for an update to our Big Board -- and today we've got a twofer with both a prospect rankings update and an expansion from a post-NCAA Tournament top 50 to a fresh top 75.

These rankings reflect the view of yours truly and how I view the class. It is not how teams and talent evaluators view it. So the criteria for how I compile these rankings as opposed to my mock draft -- with teams needs typically taken into account -- differ significantly. Imagine if you will that I am a GM of an NBA team and held every single pick in the draft. This is the order in which I would make my selections.

Movement in the top 10 of our new rankings is minimal from our last update. And while there are a few new names sneaking in to that mix and some reshuffling throughout, this update is mostly to provide a clearer picture of the landscape along with an idea on what ranges prospects may fall now that things are starting to come into focus. So with that in mind, a refresh on our rankings is below with some highlights of some notable risers and fallers. 

Click here for updated CBS Sports Top 75 NBA Draft prospect rankings

Notable risers

Scottie Barnes | Florida State | SF 

Previous ranking: 17
Current ranking: 9

*timidly raises hand* I'll admit it: I've not been a Barnes believer throughout the draft process. Not until recently, having last had him at No. 17 on the Big Board. I'll also freely admit that I think with more studying, that was an overthink. Now, there are still very legitimate questions about his prospects and pokeable holes in his game -- he made 27.5% of his 40 attempts from 3-point range in college and wasn't much of a scoring threat, with his shot still needing improvement. But he's a 6-foot-9 forward who can create on offense, brings a ton of defensive versatility and has an incredible pedigree, profiling as someone I'd like to gamble on. If the shot can improve he can be a real difference-maker who gives a team tons of versatility on both ends of the court. Even if it doesn't, he's going to be a useful defender and a plus-playmaker from his position.

Josh Giddey | Adelaide 36ers | SF 

Previous ranking: 28
Current ranking: 11

Josh Giddey is the biggest and most noteworthy riser in this update. His stock is soaring overseas, where for the Adelaide 36ers he's emerged as a first-class playmaker, reaching double figures in assists in three of his last five games as an 18-year-old in the NBL. The combination of Giddey's 6-8 frame, passing instincts and ability to read plays has him as a likely lottery pick at this stage. Holding him back from surefire top-10 status is inconsistent shooting (68.2% from the free-throw line and 31.1% from 3-point range) along with just-OK athleticism. Still, big wings who can create and pass the way Giddey can should have a shot at sticking as a role player, and the upside he has if the shot really starts falling could make him a mid-first-round steal. With each game he's solidifying himself as the best international talent in this draft. 

Joel Ayayi | Gonzaga | SG

Previous ranking: 40
Current ranking: 29

There was Drew Timme and his incredible mustache, and Jalen Suggs and his special season, and Corey Kispert and his flamethrowing. But for Gonzaga this season, there was, quietly, Joel Ayayi, posting a career-best 12.0 points and 6.9 rebounds per game on 38.9% 3-point shooting. The 6-5 shooting guard was often overlooked in the grand scheme of Gonzaga's greatness but he showed top-end role player traits and -- given the opportunity -- showed even more than that, though the Zags' loaded roster allowed for few of those opportunities. Teams may want to take stabs at younger players with more perceived upside late in the first round but in the late first, he could be a winning addition to a contender. 

Notable fallers

Kai Jones | Texas | C

Previous ranking: 8
Current ranking: 13

When it comes to Kai Jones, the selling point for him boils down to one word: upside. At 6-11 with freakish athleticism, he moves like he's 6-6 and was able to showcase some interesting skills at Texas. But using the word upside to talk about Jones is also the kind way of acknowledging that, while he has great potential, he also has a potentially long developmental track. Needs to get stronger and definitely not ready to make an impact right now in the NBA. It won't at all surprise me if a team bets on his talent early -- potentially in the top-10 -- but it's a gamble on his potential and not necessarily on what he's consistently shown, which is why I've dropped him down a few spots. There are a few more safe players in this class I'm ranking ahead of him for right now because his prospects are a tad more volatile than others in this range. But if you are truly drafting on players most likely to be stars, Jones fits the profile of someone who could hit and make some GM look incredibly smart down the line. 

Ayo Dosunmu | Illinois | PG

Previous ranking: 18
Current ranking: 25

I have prided myself on being the high guy with Illini star Ayo Dosunmu -- and at 25 I still am -- but I've dropped him down a few spots in favor of some one-and-dones like Auburn guard Sharife Cooper, Kentucky big Isaiah Jackson, Stanford wing Ziaire Williams and Duke combo forward Jalen Johnson. Dosunmu still has a first-round grade here from me, and I will continue stanning his NBA prospects. But I think this ranking more accurately reflects where he'll go, as it's likely he'll be more of a combo guard asked to shoot in the NBA than a lead guard like he was in college (or some hybrid of that as a strong backup lead guard). Either way, he's still likely landing in the first round and the later he slips, the bigger win it's likely going to be for a team like the Nuggets, Clippers or Lakers hoping to pick up an experienced college player with instant impact potential.