As a Sox fan and witnessing the daily soap opera, I feel that Manny* didn't become a "clubhouse cancer" until last season, when he obviously quit on the team to get out of those burdensome $20M option years in his contract.
Don't get me wrong, he was quirky, he appeared to be lazy on the field, and it was obvious he always thought of himself first. But, I never saw any "mood swings" and, he never did anything detrimental to the team until last year. All in the name of cashing in on that fat contract....
He was never a "clubhouse cancer" during his tenure with the Indians either.