In the regular season, the Boston Celtics were one of the deepest teams in the league. Beyond their obvious superstar duo of Jaylen Brown and Jayson Tatum, the Celtics boasted a veritable cornucopia of useful bench players. The guard troika of Derrick White, Marcus Smart and Malcolm Brogdon was sneakily one of the best backcourts in the entire NBA; Al Horford and Robert Williams formed a dominant big man battery. Deeper down the bench, guys like Payton Pritchard, Grant Williams, Mike Muscala and Sam Hauser all flashed moments of genuine utility. Come the postseason, though, the rotation shrank; playoffs basketball is so intense that being good enough is no longer grounds to get on the court. As such, the cash-strapped Celtics need to beef up their rotation in free agency by adding a guy who's just as productive in the season's final 16 games as he is for its first 82. Here are three players that the Celtics must go after in free agency this offseason.

Seth Curry

The Celtics won't really have much money to work in the offseason—their financial constraints guarantee they won't get a great player in free agency, but it doesn't necessarily preclude them from adding a good one. Accordingly, Seth Curry could be the perfect marriage of affordability and ability. Against the Miami Heat in the Eastern Conference Finals, the Celtics were partially done in by their icy three-point shooting. Luckily, Curry could offer a one-man remedy. As one of the best shooters in the history of the sport, Curry would lend the offense an entirely new dimension. Outside of labored Tatum side-step threes, the Celtics never really established a way to put pressure on defenses from the perimenter. Even nominatively very good shooters like Brown or Brogdon were passive threats—they wouldn't shoot unless they were open and they wouldn't be open unless a defense let them get open.

Conversely, Curry is a masterful off-ball shot creator. When he hunts jumpers and curls around screens, he looks eerily like his brother Steph. When he sets his own screens (or ghost-screens), defenders instantly panic. Although Curry doesn't create his own shot particularly well, his shooting gravity warrants constant attention from opposing defenses. No matter how far Curry is away from the play, opponents must have some sort of contingency plan to keep him from shaking loose from three. He foments mental exhaustion. The Heat were able to bottle up Tatum and Brown by sinking all of their energy and effort into stopping the Celtics' star duo; Curry would offer a much-needed distraction.

Mason Plumlee

Losing to the Heat unearthed some glaring flaws that the Celtics must address this offseason. Namely, the Celtics need to upgrade their center and power forward spots in order to make it to the next level. Al Horford is theoretically the perfect fit, but he's reached the point of his career where his immobility renders him a taller PJ Tucker. Robert Williams is an elite rim protector and lob threat when he's healthy, but comes with the unfortunate side effect of never, ever being healthy.

Plumlee would be the perfect solution in free agency to ameliorate some of the Celtics' big man problems. He's sturdy enough at the rim and on the glass that he can hold down the fort on his own; he's skilled and smart enough that he can crack open slivers of space when he shares the court with another center.

For a not insignificant portion of the winter, Plumlee was legitimately as productive as just about any center in the league. Playing out the string on a godless Hornets team, Plumlee sneakily leveled-up into a convincing Bam Adebayo facsimile, overpowering players on the interior with his athleticism, yet also outfoxing and outskilling teams with his offense. For a player his size, Plumlee is a special ball-handler and passer; there are only a handful of players who are more dangerous fulcrums in a dribble handoff. He dusts overeager bigs off the dribble; he picks out cutters with Jokic-like precision; he even busted out a goofy, shockingly accurate lefty floater. As a Celtic, he wouldn't merely allow them to hide some of the team's weaknesses—he would accentuate previously unseen strengths.

Dillon Brooks

Presumably, Brooks is out of Boston's price range; unless he pokes dozens of literal bears and loses at least 1.5 limbs in the process, there's no real scenario where Brooks signs with the Celtics in the offseason for a piddling five million dollars. But if the Celtics could swing a deal, Brook would inject that dog in them. Brooks is a menace, for better or worse. But while it makes sense why an over-active Memphis team would cut ties with Brooks, he'd give the Celtics a much-needed jolt of crazy. The problems with the Celtics are entirely mental—their shared neuroses were so unmanagable that they overshadowed  Boston's elite talent. In this sense, Brooks would be a needed pain-sponge for Brown and Tatum. Either Brooks' grit and lockdown defense inspires the rest of the roster to match his energy—or he blows up so spectacularly that nobody has any bandwidth to criticize anybody else on the Celtics. Win-win.