The conventional wisdom in the Eastern Conference centers around a season-long collision course between the Boston Celtics and Milwaukee Bucks. Those are the only Tier 1 championship contenders, and everybody else is at least a rung or two down the ladder. 

That may well turn out to be the case. In terms of recent playoff history and a general sense of stability, the Bucks and Celtics are miles above the Philadelphia 76ers. If star power wins the day, the current construction of the Miami Heat isn’t well-positioned to compete. 

Yet the curious thing is you could have said the exact same thing had Boston and Milwaukee not made any significant changes to their rosters this past offseason. Instead, each one took a sledgehammer to its identity and a large part of what had made it so great over the last few years. 

It’s easy to see the upside in pairing Damian Lillard with Giannis Antetokounmpo and adding an offensively gifted big man like Kristaps Porzingis to the mix in Boston. But what about the risks of making such a major philosophical change to teams that had played a certain way and won a certain way? If you’re Philly or Miami, and maybe even Cleveland, New York or Atlanta, there should be just enough uncertainty to believe there’s an opportunity to crack the Eastern Conference finals. 

The case for Milwaukee is obvious. Over the last five seasons, the Bucks have finished with the best record in the East three times and have been the third seed twice. In one of those No. 3 seed years, 2021, they won the championship. 

There was nothing fundamentally wrong with the Bucks last season when they went 58-24, but their playoffs ended quickly after Antetokounmpo hurt his back early in Game 1 against the Heat. Though Antetokounmpo returned by Game 4, he wasn't 100 percent and the damage was done.

Instead of using the injury as an excuse, the Bucks fired Mike Budenholzer and hired first-time head coach Adrian Griffin. Then when the opportunity to acquire Lillard presented itself, they pounced — even though it required giving up Jrue Holiday. 

Swapping Holiday for Lillard obviously makes the Bucks more dynamic offensively. He is one of the elite shooters in the history of the NBA, which will theoretically open up more space for Antetokounmpo, and a proven crunch time shot-maker in playoff games. As great as Holiday was in Milwaukee, his shooing percentages for the last three playoffs were 40 percent (28.6 percent from three), 38 percent (31.6 percent from three) and 41 percent (30 percent from three). 

Lillard will bring more offensive dynamism when things grind to a halt as they sometimes did for Milwaukee in the playoffs. But he’s also got to guard somebody, and he’s never been very good at that. 

In a playoff series against, say, Trae Young or Jalen Brunson or Darius Garland, you could count on Holiday to do the bulk of the necessary defensive work to make life difficult. But responsibility on that end of the floor will now shift even more heavily toward Antetokounmpo and Brook Lopez, who is 35. 

In theory, Milwaukee has enough plus-defensive players to deal with a dynamic point guard who can break Lillard down over and over again during a playoff series. But that’s just a theory, and having a first-time head coach is yet another variable that nobody can be sure about until we see it in action. 

The philosophical shift in Boston is, in some ways, even more interesting and risky. For the last few years, the winning formula for the Celtics has started on the defensive end with a ton of versatility on the perimeter, a lot of outside shot-making and incredible depth. Especially in the regular season, Boston could bring in four guys off the bench that could bomb threes and make it easy for the starters to come back in and finish the job. 

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Boston’s two big moves to add Porzingis and pick up Holiday on a boomerang from the Lillard trade gives the Celtics the best top-four in the East with Jayson Tatum and Jaylen Brown. 

But they had to give up a lot to make that happen. Marcus Smart, a huge part of their identity and defensive capability, is now in Memphis. Malcolm Brogdon and Rob Williams, who was a major X-factor defensively when healthy, are in Portland. Grant Williams is in Dallas.

A team that often went 10 deep is now much more limited outside of its top six — and one of those players, Al Horford, is 37. 

Holiday is a better player than Smart and should fit in well. But is a front court of Porzingis, Horford and Luke Kornet enough to do the kind of rebounding and shot-blocking work that solidified Boston’s defense in past seasons? And without as much depth or 3-point shot-making to rely on through a long season, even one injury becomes a much bigger deal.

At minimum, it’s a different approach to basketball than the one that has gotten Boston close to winning a title. And its success is probably going to come down to whether Porzingis, who has been a polarizing player over the course of his career, can play winning basketball on both ends of the floor. 

In eight seasons (he missed one of them due to injury), he's played in a total of 10 postseason games, all with the Mavericks. But his contribution to those teams was so lightly regarded that Dallas pretty much dumped him to Washington for very little in return. 

Porzingis rediscovered his form in D.C., averaging a career-high 23.2 points on excellent efficiency. But putting up numbers on a team that went 35-47 and never had much hope of making the playoffs is far different than what he’ll be asked to do with the Celtics. 

If Boston gets that Porzingis, it will be vindicated. If it gets the version that fit poorly with the Mavericks, there could be an opportunity for someone else to contend in the East. 

Follow USA TODAY Sports columnist Dan Wolken on X @DanWolken