There are definite issues with the stat. It cannot measure that baserunning, for example. It only knows the outcome of the play, not why it came that way.
It really is meant to measure how clutch a player was in the moment. For example, if the Twins score 8 runs in the first, but Lewis makes two outs that inning, and then hits four home runs later, he likely has zero wpa. But he has lots of positive war. Wpa figures what he did didn't matter that game, war measures value independent of the context, because it's trying to measure seasonal value.