Paul Pierce says that if he had to choose between the Celtics' or Raptors' roster for the rest of the season, he'd choose the Raptors. (1:32)

When LeBron James finally abdicated his throne atop the Eastern Conference last summer, there was always going to be a scramble to fill the power vacuum.

No one could have anticipated just how much of a scramble it has become.

Thanks to the combination of their play and the moves they have made, four teams -- the Milwaukee Bucks, Toronto Raptors, Boston Celtics and Philadelphia 76ers -- can make credible cases to succeed James as the opponent for the Golden State Warriors (barring something completely unexpected happening out West) in this year's NBA Finals.

While all four of those teams have obvious strengths, they each have clear weaknesses that can be exploited by their opponents. So, as these teams head into the final six weeks of the regular season, here is the case for -- and against -- each of these four contenders for the throne.

Milwaukee Bucks

The case for ...

play 1:41 McGrady: Bucks' ceiling is at least Eastern Conference finals Tracy McGrady and Brian Windhorst join The Jump to discuss the Bucks' ceiling, as they own the No. 1 seed in the Eastern Conference.

Giannis Antetokounmpo has grown from a gangly teenager into a 6-foot-11 version of the Incredible Hulk, and he is obliterating everything and everyone in his path. Not only is he the best player in the East, but he is now arguably the best player in the entire world, thanks to his ability to dominate the game at both ends.

The Bucks, meanwhile, have easily been the NBA's best team this season, posting a 9.4 net rating -- almost three full points higher than the Warriors. With the fourth-ranked offense and the top-ranked defense, Milwaukee is the only team with two units inside the top five and one of three (along with the Raptors and Sixers) with two in the top 10, which is a typical indicator of a serious championship contender.

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Milwaukee's overnight evolution from a run-of-the-mill playoff team into a championship contender is powered in large part by coach Mike Budenholzer, who has given this team coherent structure at both ends of the court. The Bucks, perhaps more than any of these other squads, know exactly what they are: a team that is going to space the floor with 3-point shooters around Antetokounmpo to give him room to attack offensively, and one that is going to build a brick wall around the paint defensively. The results speak for themselves.

That identity gives the Bucks one significant advantage over the competition in the East: They have so far played with near-perfect chemistry. The Celtics, Raptors and Sixers all have issues to sort out. The Bucks, on the other hand, have a team full of players who know exactly what their roles are and have bought into them.

Chemistry is perhaps the most underrated thing in basketball -- and the Bucks have it.

Then there's the most obvious advantage: Milwaukee is on the way to having the top overall record in the East -- which means home-court advantage. Considering how much better each of these four teams play at home, getting the chance to have an extra home game in each playoff series is a significant edge.

The case against ...

Will Giannis Antetokounmpo's lack of outside shooting hurt the Bucks in the playoffs? Jesse D. Garrabrant/NBAE/Getty Images

Antetokounmpo might very well be the best player in the world, but he is not the best option in the clutch. Because of his still nascent perimeter-shooting ability, it can be tough to hand him the ball in the final moments of a game and ask him to make a shot, like the Celtics can with Kyrie Irving. That flows into the next point against the Bucks: the lack of a traditional second star on the roster. Khris Middleton was an All-Star this season, but he doesn't have the profile of a typical second star on a championship-level team. If Antetokounmpo is Shaquille O'Neal, for example, the Bucks don't have their Kobe Bryant to go with him.

Budenholzer saw his Atlanta Hawks teams struggle to replicate their regular-season success in the playoffs. Some of that could be attributed to the same thing that all of these teams are happy to be avoiding this season -- James' domination of the conference -- but some of it was because Budenholzer's philosophies (particularly allowing opponents to fire away from deep) didn't translate.

The other issue, though, is the most obvious: These Bucks haven't been here before. None of the key contributors on this team has been a pivotal member of a team that has made a deep playoff run. Antetokounmpo and Middleton have never even won a playoff series. Remarkably, the Bucks as a franchise have advanced past the first round of the playoffs just one time in the past 30 years.

That isn't a guarantee of failure; the Warriors, after all, had won one playoff series over the prior two seasons combined before breaking through and winning the title in 2015. But teams don't typically skip steps in the NBA. If the Bucks are to break out of the East, they're going to have to leap up an entire set of stairs.

Toronto Raptors

The case for ...

play 0:49 Ujiri: Toronto has advantage vs. other teams Raptors president Masai Ujiri explains why running a team in Canada in some ways gives him an advantage over the other 29 franchises.

If Antetokounmpo isn't the best player in the East, Kawhi Leonard is. While Leonard might not be quite at the same defensive level as he was before missing most of the 2017-18 season, he is still one of the most dominant two-way forces in the NBA. He has transformed Toronto from a team destined to disappoint to one that has a real shot to escape the East. Anyone who doubted that transformation just needed to see how the end of Friday's Raptors-Spurs game played out, as Leonard simply ripped the game away from DeMar DeRozan.

After trading for Leonard and Danny Green during the offseason, and adding Marc Gasol and Jeremy Lin this month, the Raptors are the deepest team in the East, one capable of playing in virtually any style. Raptors coach Nick Nurse has been experimenting with different lineups throughout the season, in order to prepare Toronto for the jockeying that goes on with lineups and combinations within a playoff series.

Like Milwaukee, Toronto has a shot at home-court advantage throughout the East playoffs (and if both remain ahead of the Warriors, potentially in the NBA Finals). The Raptors also have one of the better weapons to throw at Joel Embiid now that Gasol is on their roster -- which is good, considering Embiid has given them trouble all season.

In the two games the Sixers played against the Grizzlies this season while Gasol was still in Memphis, Embiid went 8-for-28. Toronto will be hoping for similar results if these teams meet up this spring.

The case against ...

Kyle Lowry is no stranger to postseason disappointment. AP Photo/Eric Christian Smith

DeRozan's return last week was a celebration of nine really enjoyable years in Toronto, which saw the Raptors become a factor in the NBA. But it also was a reminder of something else: the crushing disappointment this team felt year after year when the playoffs arrived. DeRozan and his backcourt mate, Kyle Lowry, were the faces of this franchise's turnaround -- as well as repeated disappearances in the postseason (and James turning Toronto into "LeBronto" repeatedly).

While Budenholzer's playoff history has some warts, Nurse doesn't have one at all -- which makes it a question mark, if not necessarily a negative. His willingness to experiment this season and getting players to buy into their roles has been impressive. But doing that in the regular season and doing it in the playoffs are two very different things.

Toronto also has had a chaotic season. Lowry and Leonard have only played together in 32 of Toronto's 61 games. The Raptors only have had two games this season in which their entire roster was available to them. The fact they are still performing as well as they are is a credit to them, but it also is going to leave them with a decided lack of cohesion headed into the playoffs.

The other area of concern with this team is 3-point shooting. Toronto is the worst of these four teams in 3-point percentage at 34.8 percent. It's not a coincidence that the Raptors have struggled this season to beat the Bucks, who are happy to let teams fire away from deep if it means stopping them from getting to the rim.

Boston Celtics

The case for ...

play 1:53 Tatum: Celtics will win the Finals this year Jayson Tatum, winner of the NBA skills competition, guarantees the Celtics will win the 2019 NBA Finals, and he reacts to being involved in trade talks.

For all of the weirdness the Celtics have had this season -- and they've had plenty -- they also have a style of playing against strong competition that has worked. They play a tight game led by strong defense, keeping it close until the final five minutes, then let Irving carry them home to a win. Irving arguably would be the consensus first choice to take a pivotal shot late in a game, given the amount of times he has done so in the past. For example: In overtime this season, Irving is 10-for-16 from the field -- and Boston is 4-0 in those games, including wins over Philadelphia and Toronto.

Beyond Irving, Al Horford creates a matchup nightmare for all three of the other East contenders. Embiid is flummoxed by him every time they play, and Horford also has the ability to make life miserable for Gasol and Toronto teammate Serge Ibaka and Milwaukee's Brook Lopez. Horford was the second-best player in the East playoffs last year; this year, he could be the most important player in the East playoffs.

The other strong point in Boston's favor is its accumulation of playoff success. Irving has one of the most important shots in NBA history -- the winner in Game 7 of the 2016 NBA Finals -- to his name. Boston's young players helped spur the Celtics to the East finals without Irving or Gordon Hayward last season, and while Horford has never had ultimate success in the playoffs, he has played in 111 postseason games.

The case against ...

Gordon Hayward has been inconsistent in his first season back from the devastating injury he suffered in October 2017. Adam Glanzman/Getty Images

Despite the expectations the Celtics had entering this season, they might have the lowest ceiling of any of these four teams. Boston has that one surefire way of playing against elite competition, but it is unclear if the Celtics can succeed against the opposition playing another way.

Hayward's inconsistent play is understandable, given the injuries he is recovering from, but it doesn't make it any easier for the Celtics to adjust to, not knowing which version they'll get on a nightly basis.

That same inconsistency also factors into what has been an ongoing issue: the chemistry issues within the team. From the on-again, off-again public spats between Irving and the team's young players to Boston's general ups and downs throughout the season, it has been a frustrating campaign after sky-high offseason expectations.

It also seems almost certain that the Celtics won't have home-court advantage beyond the first round -- and maybe not even in it. That will make the task of advancing all the more difficult.

Philadelphia 76ers

The case for ...

play 1:55 McGrady: The 76ers are the favorite in the East Tracy McGrady breaks down why after the Tobias Harris acquisition, the 76ers are the team to beat in the Eastern Conference.

After trading for both Jimmy Butler and Tobias Harris this season, Philadelphia now has a starting five -- Ben Simmons, JJ Redick, Butler, Harris and Embiid -- that is better than any in the NBA outside of Oakland (and could maybe even give the Warriors a run for their money, given DeMarcus Cousins is nowhere near his pre-injury form).

Some might even call it Phantastic.

That group gives the Sixers arguably the highest ceiling of any of these teams. Being able to play those five guys for 40 or more minutes in a playoff series is the biggest advantage Philadelphia will have in the postseason.

It also will allow the Sixers to do what the Warriors have done with such success: have at least two of the starters on the court at all times. That can give Philadelphia the ability to take advantage of any second-unit lineups their opponents throw on the court against them.

The case against ...

The 76ers have made drastic changes to their roster this season. Mitchell Leff/Getty Images

The byproduct of making blockbuster trades for Butler and Harris -- along with moving on from Markelle Fultz -- is that the Sixers now have six rotation players who were not on the roster when the season began. There is a reason teams don't often go on to huge success in the playoffs after midseason shakeups: Chemistry is a real thing, and it doesn't happen overnight.

Philadelphia has remade its roster on the fly, and now it has to try to figure out where to go from here with just a quarter of the season remaining.

And for as Phantastic as Philadelphia's starting five is, its bench is equally weak. Mike Scott is a solid bench scorer and T.J. McConnell is a serviceable backup point guard, but both Jonathon Simmons and James Ennis III are inconsistent presences on the wing. While the Sixers have been insistent on playing him in all matchups, Boban Marjanovic has proved to be much more of a specialist.

The other issue Philadelphia has is a general lack of shooting. In the various moves that the Sixers have made, they've shipped out three players -- Robert Covington, Wilson Chandler and Landry Shamet -- who each are shooting at least 39 percent from 3-point range this season. Outside of Redick and Harris, there isn't a single above-average shooter on Philly's roster.

Average, inconsistent shooters also tend to struggle more on the road -- somewhere the Sixers, like the Celtics, seem certain to have to win to advance. Both teams trail the Indiana Pacers right now, meaning there's even a chance they'll face each other in the first round. That would mean the Sixers or Celtics would face the possibility of three straight series as a road underdog to make it to the NBA Finals.

Considering only two teams under the 16-team playoff format -- the 1994-95 Rockets and the 1998-99 Knicks -- have been lower than a 4-seed and reached the NBA Finals, it would be a situation best to avoid. But based on the way things are going, it might be unavoidable for one of them.