This time last year, the Boston Celtics knocked off the Milwaukee Bucks in the first round of the playoffs in seven games. Now, they'll meet again, though this time pretty much everything will be different.

This season's matchup is in the second round, the Bucks will have home-court advantage, Mike Budenholzer and Brook Lopez arrived in Milwaukee and overhauled the Bucks' entire system, turning them into one of the best teams in the league and, of course, Kyrie Irving and Gordon Hayward are now healthy. Even the stakes are higher.

The Bucks (60-22) just put together one of the best regular seasons in franchise history, and led the league in wins. After cruising past the Detroit Pistons in the first round for their first series win since 2001, this will be an important test to prove they're built for the playoffs. As for the Celtics, they struggled through the regular season, dealing with all sorts of drama, both self-inflicted and not. A second-round playoff exit was not what they had in mind heading into the season, and if it happens, it could have quite an impact on their summer -- specifically in regards to Kyrie Irving.

So how might this series go? Here's a look at a few keys that could decide the series.

Brook Lopez vs. Al Horford

When Lopez arrived in Milwaukee this summer, the move was praised far and wide as a fantastic signing. But even the Bucks couldn't have expected just how big of an impact Lopez would have on their team.

The Bucks veteran drains 28-foot 3-pointers on a regular basis, and his ability to space the floor that far out has opened up all sorts of space for Giannis Antetokounmpo to operate inside. On the other end, Lopez anchored the best defense in the league in the regular season, and proved to be an impressive rim protector.

But in the Bucks' drop-back defensive system that allows Lopez to command the paint, 3-point shooters are often left open. In particular, that's the case on pick-and-pops when the screener floats out to the 3-point line. Against certain teams and matchups, that can cause a problem for the Bucks. One of the worst matchups in that regard just so happens to be Al Horford.

Much like Lopez himself, Horford has turned himself into a strong 3-point shooter in the latter stages of his career. Though his efficiency dropped a bit this season, Horford still knocked down 36 percent of his attempts from downtown, and is one of the best outside-shooting bigs in the league.

During the regular season meetings between the two teams, the Celtics crushed the Bucks when Horford and Lopez were both on the floor, outscoring them by 28 points in 44 minutes. In minutes where those two are each playing the five, the Celtics can get an open 3 for Horford pretty much any time they want. With how Lopez and the Bucks play, they're just going to concede that shot.

But this is also why the playoffs are so interesting. Will the Bucks or Celtics change their lineups in order to try and avoid or exploit that matchup? For example, the Bucks could go to Giannis Antetokounmpo at the five, while the Celtics have recently been starting Aron Baynes at center. Will the Bucks perhaps adjust when Lopez and Horford are both on the floor to try and surprise the Celtics? We'll just have to wait and see.

Eric Bledsoe vs. Kyrie Irving

When these two teams met in the playoffs last season, Bledsoe was straight-up embarrassed by Terry Rozier. Playing in place of the injured Irving, Rozier frustrated Bledsoe to such an extent that the Bucks point guard tried to pretend he didn't know who Rozier was.

To his credit, though, Bledsoe has come back with a vengeance this season, and turned himself into arguably the second-best player on the Bucks. He's done well running the show in the Bucks' revamped offensive system, but the most important improvement has been on the other end of the floor.

Describing himself as a "pitbull," Bledsoe has been locked in on defense all season long, where he's become a master at fighting over and around screens. Part of the reason the Bucks' drop scheme works so well is because Bledsoe is relentless in hounding opposing ball-handlers and disrupting what they're trying to do.

That ability will be crucial against the Celtics in this series, as they boast one of the best scoring point guards in the league in Kyrie Irving. With Lopez sitting so far back in the paint, Bledsoe's margin for error is pretty small in general, but will be miniscule against Irving. If he gets caught up on a screen, or loses focus for even a split-second, it's too late.

In the regular season, though, Bledsoe showed he's capable of doing the job. During their three regular-season contests, Irving shot 13-of-36 (36 percent) from the field when Bledsoe was guarding him, per the NBA's tracking data. That's nearly 13 percent less than Irving's season average from the floor of 48.7 percent.

Bledsoe has the right combination of strength and quickness to bother Irving and make his life difficult. Irving might end up making a bunch of tough shots, because he's an elite scorer and has a proven track record of stepping up his game in the postseason, but at the very least, Bledsoe is going to make him work for his buckets.

3-point shooting

The 3-pointer has well and truly taken over the league, with every team hoisting at least 25 triples per game in the regular season -- a mark that would have led the league in 2007. But few teams embrace the 3-ball like the Bucks.

When Mike Budenholzer arrived in the offseason, his first plan of action was to find shooters in the free agency bargain bin and turn the Bucks' offense into Giannis surrounded by shooting. It was a smashing success, as the extra space created all sorts of room for the Greek Freak to operate inside, where he dominated. And if the defense collapsed on him, or any other driver, there would be always be an open shooter somewhere on the floor.

The Bucks launched over 38 3s per game on average, a mark second only to the Houston Rockets, and were also second in the league in makes, at over 13 per game. Though they weren't the most efficient shooting team -- 35.3 percent, 15th in the league -- their volume more than made up for it, and their 3-point attack was a major reason they finished with the fourth-best offense in the league.

But while the 3-pointer is an important weapon for them on the offensive end, it can also be their downfall on the other end of the floor. The Bucks gave up 36 3s per game this season, which was the most in the league and opponents shot over 36 percent on them -- the worst 3-point percentage allowed of any playoff team. That was the shot the Bucks had to sacrifice in their defensive scheme which focuses on protecting the paint and rim.

Over the course of the season, that scheme was successful, and they were the best defense in the league in the restricted area, allowing opponents to shoot just 58 percent. But they do give up open 3s, and in a short series, against a good 3-point shooting team, that could potentially be a problem. As we saw in the first regular-season meeting between these two teams, when the Celtics knocked down 24 triples en route to victory, Kyrie and Co. can shoot the ball.

Seventh in both 3-point attempts and percentage in the regular season, the Celtics will provide much more of a challenge in that respect than the Pistons, who were one of the league's worst 3-point-shooting teams. Especially when they go small, the Celtics will have strong shooters at every spot on the floor. Seven different rotation players made at least 34 percent from 3 in the regular season, and that doesn't include Gordon Hayward, who is a completely different player now than he was for most of the season.

With strong 3-point attacks a focal point of each team's offense, this series could very well swing on which team shoots better from downtown.