That Yaz that played hurt and healed while playing was the MVP of the playoffs against the 3 time defending champion Oakland A's. He made some unbelievable defensive plays and he hit something like .450 including a key HR against Vida Blue. Without Yaz, they don't' even get to the WS.
Sitting out longer wasn't going to make the long term healing any more complete. Anyone who has had a bad sprained ankle could tell you that it is never the same.
So, yeah I am happy that Yaz toughed it out and played through his injury, because without him we would have missed watching the 1975 World Series, and he played pretty darn well in that WS too.
As for 1978, Yaz's backup was likely to be Pot-Bellied Bob Bailey. Ten percent of Yaz was better than Bailey. I am glad Yaz taped up and went out and hit a second inning HR against the untouchable 25-3 Ron Guidry and he got another knock against Gossage. There was no one on the bench who could have done that for the team. You just don't know what you are talking about when you talk about Yaz.