Seahawks coach Pete Carroll said Monday that Pitts suffered a serious concussion Sunday night against the Rams, while Baker fractured a bone in his hip.
Pitts started five games this season, but was benched last week in favor of Tyler Polumbus. Pitts played briefly in the first half Sunday after tackle Russell Okung was out for a short time and Polumbus shifted to tackle.
Baker had one catch for 1 yard on Sunday. He had nine catches in the regular season.
Carroll also said receiver Brandon Stokley (head) would be questionable for this week after being inactive on Sunday.