The Celtics have been dealing with plenty of injuries to key players this season and they've just suffered another. According to Shams Charania of Yahoo! Sports, Daniel Theis is going to be out for the rest of the season due to a torn meniscus in his left knee. The injury to Theis occurred in a loss to the Pacers on Sunday.

Theis has been a bit of a surprise for the Celtics. Expected to just provide rotation minutes, he has turned into one of their better big men and has filled the role well when guys like Al Horford have to sit out. He won't be an easy player to replace.

The loss of Theis could mean a lot more minutes for Greg Monroe and even Aron Baynes. Having Baynes fill in shouldn't be a problem considering he has already been a major part of the rotation all season. Monroe, however, could be an issue. He was a midseason signing that really has just provided depth and some more size. He is also nowhere close to the same caliber defender as Theis.

The Celtics can't shake the injury bug. Kyrie Irving has been in and out of the lineup with a sore knee. Horford has occasionally missed time and Jaylen Brown is in concussion protocol. Boston could be a threat in the playoffs, but only if the Celtics are healthy when they get there.