First Rajon Rondo, and now Jared Sullinger. In a rather cruel twist, the Boston Celtics lost their promising rookie forward and most efficient rebounder to back spasms last night -- only days after the devastating Rondo news sent shockwaves throughout the NBA community. It's still unclear as to how long Sullinger will be sidelined, but this injury can't be a good sign for an inconsistent team suffering from an identity crisis minus its mercurial floor general.

According to 82games.com, Boston's most effective five-man unit without Rondo this season has been the Terry-Lee-Green-Sullinger-Garnett lineup, and the rebounding efficiency of Sullinger -- and Kevin Garnett, of course -- undoubtedly plays an important role, albeit not the only one. Given extended opportunities, the Ohio State product registers about 14.2 rebounds per 48 minutes, an unworldly share of misses when you consider the familiar names trailing him in the rankings: David Lee, Joakim Noah, Roy Hibbert, DeAndre Jordan, and Marcin Gortat are only a few examples. Sullinger's rebound rate ranks among the league's best, not to mention that he's been Boston's most dedicated offensive rebounder thus far and continually limits opposing teams' transition opportunities when he pursues unsuccessful shot attempts. If Sullinger misses significant time moving forward, the Celtics' rebounding woes will only worsen and worsen -- a brutal reality that could also spell trouble in other categories, such as offensive efficiency, transition defense, and so forth.

Rebounding remains a must-have, and don't let the Miami Heat's postseason success fool you. Doc Rivers doesn't have an unprecedented embarrassment of riches -- headlined by perhaps the most talented player ever born -- at his disposal. Surrounding LeBron James with Dwyane Wade, Chris Bosh, and a full deck of proven three-point shooters isn't a viable option for Doc's coaching staff, so they must make do with the pieces given to them. Throw in the fact that the Terry-Lee-Green-Sullinger-Garnett lineup represents the Celtics' most effective five-man unit on a strictly plus/minus basis, even counting Rajon Rondo -- it's not even close, actually -- and Jared Sullinger's injury leaves a certain void.

Yes, the fumbling, bumbling Celtics are bound to move some pieces before the trade deadline, and maybe even some of the big guns. This is a point-guard-less assembly of parts in absolute flux. However, another injury certainly stings in the short run. Yes, he's only a rookie. He fouls a lot. He can't jump. He's not quick from side to side. He doesn't really space the floor. But, please, don't be mistaken.

Jared Sullinger is vitally important, and his potentially prolonged absence only amplifies the sustained misery brought on by this frustrating season.