After missing the first four games of the season with a torn ACL suffered in the final game of the regular season last year, Mendenhall came back against the Eagles in Week 5 and ran for 81 yards and a touchdown.
However, Mendenhall's second game of the season wouldn't go anywhere near as well. He was listed as probable with a knee injury, yet still attempted to play. However, after only six carries for six yards against Tennessee, Mendenhall would re-injure his Achilles', per NFL Network's Alex Flannagan:
Steelers running back rashard mendenhall's return questionable with what steelers are calling Achilles. Coming off knee surgery.
— Alex Flanagan (@Alex_Flanagan) October 12, 2012
Mendenhall's injury is obviously a blow to the Steelers offense, as he is their primary running back. But fantasy-wise this is a major blow.
Last season, prior to his injury, Mendenhall ran for 928 yards and nine touchdowns, while also nabbing 18 catches for 154 yards. That type of production makes him a valuable piece for any team.
But with his recurring injuries, Mendenhall is a major question mark for the rest of the season.
It's doubtful that you would get much while attempting to trade him, but he is still a valuable asset to have on your team if healthy, due to Issac Redman taking a helmet to the knee in the third quarter. Keep him on the bench and only start him once his and Redman's statuses are found out.