The Celtics have been forced to revamp their roster this offseason as an acceptable consequence from signing Gordon Hayward. As they continue to build through the draft and free agency simultaneously, maintaining roster spots and payroll for their current team has become increasingly difficult.

The Celtics entered last season with a perfectly managed cap outlook, maintaining enough space to sign Gordon Hayward to a max contract without making any sacrifices beyond renouncing free agents like Kelly Olynyk. When the cap slowly dropped from a projected $108 million to a finalized $99.3 million, the Celtics were devastated. A trade was in order, requiring them to shave around $3 million off their payroll to sign Hayward and their slew of rookies from the past two drafts.

The resulting casualty was Avery Bradley, who was traded to the Detroit Pistons for Marcus Morris. While this is less of a downgrade and more of a…sidegrade?... the Celtics lost their third best player from last year, widely regarded by his peers as the best on-ball perimeter defender in the league.

The void left by Avery Bradley was vast, although it should be filled in whole by Gordon Hayward. But while Hayward has gradually worked his way to being a plus defender and an All-Star two-way player, Brad Stevens is still looking for another player to step into the role of lockdown defender. He told Chris Mannix on The Vertical Podcast that he thinks Jaylen Brown could be that guy.

"Jaylen has to become a lock-down defender for us," Stevens said. "That's where, as you go into an offseason and you are an individual player, there's a ton of things that you want to get better at, and there's a ton of things you want to add to your game. But ultimately, when you get back to your team, it's what do you do that's different to make your team unique to give yourself the best chance of adding value to winning. We need him to become that."

Brown caught up to the complexity and speed of NBA defense relatively quickly in his rookie season, eventually earning the honor of getting brutalized by Lebron James in the Eastern Conference Finals. But while LeBron and Kyrie Irving terrorized the Celtics in that series, Brown clearly established he would be back for more and be worthy of the challenge.

"He works hard," Stevens said. "He's going to continue to be good at that stuff. But especially with losing Avery, it's going to be really important that Jaylen takes the next step defensively."

With Bradley gone, Smart a perpetual sixth man be design and the Celtics devoid of an obvious second big man to slot next to Al Horford in the starting lineup, Jaylen could become a fixture at the tip this year. Regardless of whether Stevens breaks from tradition of starting another big next to Horford, Brown is going to be finishing plenty of games, which is the true measure of the player’s status on his team.

Boston still has Marcus Smart as an intimidating backcourt presence, but they are looking at Brown to replicate Bradley’s now absent magic. Stevens needs that one guy he can rely on to live in the opponent’s jersey as they work on and off-ball, giving the Celtics a go-to assignment defender to take an elite opponent out of the game. Brown could develop the top notch footwork, footspeed, reaction time, and tenacity that has made Bradley an elite defender. He learned how to read help defense last year, but now has to develop consistency against first units with a higher minutes load.

“Especially with losing Avery, it's going to be really important that Jaylen takes the next step defensively." – Brad Stevens

He'll often share the floor with the more recent Celtics number three pick, as Stevens is just as excited for the potential and versatility of Jayson Tatum. Stevens was caught by surprise at summer league when Tatum revealed significantly more defensive potential than his year at Duke promised.

"I think I was really impressed with and almost pleasantly surprised by his defensive ability. I thought he did a good job of keeping guys in front. I thought he did a good job of using his length guarding a number of different positions. It’s like we talked about with Gordon and Crowder or whoever: he might be in the bucket of a small forward if you just wanted to pigeonhole guys, but we see all of those guys and Marcus Morris and Jaylen Brown being able to play together. And that certainly is an intriguing thing to have that much versatility.

Tatum became a summer league darling for consistently flashing a high-post game that would make Kobe Bryant blush, but his coach wasn’t too concerned about that. Stevens wanted to see how his prized rookie could defend with a skinny frame and tremendous footwork.

“I was just looking really at how he would be able to defend. The offensive stuff is going to come easy to him. Maybe not easy, but he has a natural scoring ability. But I wanted to see how he would pick up what we are trying to do defensively. How his length would impact others, how he would pick up the off the ball schemes and everything else and thought he did a pretty good job.”

Stevens can see that Tatum has as much muscle mass as a middle school graduation, but is looking for him to build up his defensive awareness and anticipation rather than become a bully overnight like Brown appears to be trending toward.

“We’re not asking Jayson to go from where he is in the weight room to where he is going to be at age 25. But we can mix and match a little bit. When he is out there with Jae, we can move Jae up a spot. When he is with Semi, Semi can guard up a spot. When he’s playing with Gordon, whatever the case may be, we can mix and match depending on who we’re are playing against. There are going to be sometimes where you are going to be guarding somebody stronger than you and you are going to have to figure it out. He is going to have to use his mid and use his length and compete. That’s just ultimately what you have to do.”

Tatum’s fit as a bigger wing, or any of the guys that can fit that bill for that matter, will be placed in their roles based on circumstance as much as their own viability as a bigger wing.

“I think one of the things that’s interesting is when you ask about, ‘Does somebody have the physicality to play the stretch four?’ that will be determined by a.) their own physicality and b.) who they are guarding. Because a lot of teams also go with a smaller four, per se, or a four that used to be a three. So, it really just kind of depends night to night. But again, that’s where the strength and versatility of the other guys comes into play.”

Tatum’s time at the four will likely come during experimentation periods, in less competitive games with units further down the depth chart. But Brown is building up combat muscle and is ready to roll big. He could be the Celtic that takes the big leap this year, but his new friend and Stevens’ new shiny toy in Tatum will be following closely behind.