The understudy and the rock: Could Jaylen Brown replace Avery Bradley? Is Aron Baynes the next Amir Johnson?

Juggling his starting lineup is nothing new to Brad Stevens. Due to injury, matchups, or just plain ol’ tinkering, the Celtics had 14 different starting fives last season. Stevens’ most used combination—Isaiah Thomas, Avery Bradley, Jae Crowder, Al Horford, and Amir Johnson—only started 36 games together.

With Bradley and Johnson in Detroit and Philadelphia respectively and Thomas and Crowder in Cleveland, Brad Stevens will have to start from scratch with only Horford still in the fold. Kyrie Irving and Gordon Hayward create a new Big Three in Boston, but who joins them in the starting five? Do former Pistons Marcus Morris and Aron Baynes get the nod? Have Jaylen Brown and Marcus Smart shown enough to earn a promotion?

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Before adding, it’s important to note what the Celtics will be losing Avery and Amir. In Bradley, the team will miss its best perimeter defender. Stevens could sic AB on opposing teams’ best point guards/playmakers, allowing Thomas to conserve energy for the offensive end. Johnson was a throwback center of sorts, a stopgap 5 that would eat minutes in the paint, protect the rim, and bang with the bigs. Like Bradley’s symbiotic relationship with Thomas, Johnson’s presence kept Horford more on the perimeter. That prevented cheap fouls on defense and freed him up to be a playmaker above the break.

With Hayward now in the fold, there’s another playmaker on the floor alongside newly acquired Kyrie Irving and Hayward. In addition to easing the load on Kyrie, he will put even less pressure on the other two starters to create for themselves. Points and playmaking weren’t expected out of Johnson, but Bradley’s input on offense was a good barometer on if the Celtics were clicking on offense.

The most likely off-guard replacement going into training camp is Jaylen Brown. He started sixteen games last year while Bradley recovered from his strained Achilles and flourished in his absence. For what it’s worth, the Celtics were 13-3 in those games. His burgeoning skill set perfectly complements those of Irving, Hayward, and Horford. First, he’s a plus defender. He may not be the shutdown corner that Bradley is, but at 6’7”, the combination of his length and size makes him more versatile in the Celtics’ switching defense.

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Early in 2016-2017, Avery Bradley showed signs of development as a playmaker. He had 37 assists in the first eight games of the season, but as the season progressed, those numbers started to dip. By March and April, Bradley primarly became a catch-and-shoot shooter and his assist numbers fell to less than two a game.

Offensively, Brown made leaps and bounds in his rookie development. His jump shot had been a concern coming out of Cal and before the All-Star break, Brown was making only 30.7% of his threes, but in the second half of the season, Brown hit 37.9%. That’s just a microcosm of how quickly Brown has adjusted to the size and speed of the NBA and, more importantly, gotten better.

He also showed more confidence driving the ball off kick outs and getting to the rim against slower defenders. Brown hasn’t nearly reached his potential as a scorer, but he’s a prime candidate to capitalize when defenses focus on Irving, Hayward, and Horford. Unlike for Bradley, they won’t necessarily have to run sets for Brown because he can more easily take advantage of gaps with his athleticism and length.

Even with a revamped roster chock full of wings, the Celtics will play even more small ball next season, but I still think that Stevens will opt to at least start big. If he can buy fifteen minutes a night with Horford off the block, he’ll take it. And consider this: outside of Cleveland, many of the east’s other contenders have big men to wrestle with like Dwight Howard, Hassan Whiteside, Joel Embiid, Jonas Valanciunas, and Marcin Gortat.

Most likely, Stevens will turn to Aron Baynes to anchor the starting lineup. Bayne’s signing in late July didn’t make a lot of noise, but he’s very underrated. Here's what I wrote about him earlier in the summer:

Baynes, on the other hand, might have some uncovered potential. The Celtics got him cheap for the full RME at $4.2M and on the upswing of his career. Even in limited minutes in Detroit, Baynes showed a more diverse repertoire. He was used more frequently in the PnR and in the post and more active on the offensive glass. Baynes is a bruiser. He ranked 4th in per-36 screen assists for guys that played over fifty games last season; that puts him in the same conversation with Rudy Gobert, Marcin Gortat, and Zaza Pachulia. He’ll create a ton of space for IT and Gordon Hayward and give them a big target rolling to the rim.

Anything Baynes does on offense is gravy, because it's the Aussie's defense that gives him real value in the starting 5:

He lead the Pistons in on-court defensive rating at 98.5, nearly ten points lower than when he was on the bench. He averaged just over 15 minutes a game in Detroit and will be leaned on for similar playing time with the Celtics. Boston is going to love this guy.