Don't disagree with that. Walker showed against United his pace is going to be absolutely vital in thwarting counter attacks against us this season which was and will remain our most vulnerable area. The problem with Kolarov seemed to lie with peoples perception of trying. If somebody knows they're not going to make it back, there's really little point in sprinting and wasting energy, especially for a fullback who is required to get up and down more than anybody. Every single player is "guilty" of this on numerous instances, it was just some peoples hatred of Kolarov that made them pick it out as if it was specific to him. To suggest he didn't try was always wrong. 3 seperate managers were more than happy with him and he seemed to be a Pep favourite from the start and we all know that Pep won't tolerate a lack of effort. We all liked to see Zab trying his hardest to get back when it was never happening but in reality it's a poor decision and should have been conserving energy.
I take your point about conserving energy but I don't agree that it's the best practice. For me a player should always do his best to help his team.