I'd like to put my two cents in regarding what is perceived to be a lack of effort from Yaya.
There are two versions of Yaya: The young industrious Yaya, and the old "lazy" Yaya. First of all, we need to forget about the first version. The guy is 34, he can't be the effective box to box midfielder of the past. What he can be is an experienced, technically imperial maestro, and I don't use the word maestro lightly. The common sentiment I feel from this thread is that you need to defend to be a "proper" midfielder. One example that destroys this argument is Pirlo. Pirlo was never a defender. In fact, he barely moved in either direction whether its offensively or defensively, and he was arguably the best midfielder of this century. Does anyone here in his right mind question Yaya's technical ability and understanding of the game?
Now I agree entirely that Yaya can't slot in a KDB-Ferna-SIlva dynamic, his current style of play is very different. But he can definitely dictate play with minimal physical effort in his own slow style. Yes he won't play the Guardiola way, but he is at least an above average player by this league's standards if used correctly.
People also tend to underestimate what a cl winner gives to the team by simply existing. Make no mistake, this guy is more important off the field than on it.