Who'd he sub in for him? Torres? He did and we know how it worked out.
He even clarified how and why Schurrle was selected a striker. He said he knew Schurrle isn't proper striker and isn't going to make runs like a "real striker" but when he was upfront, Chelsea were enjoying decent possession and were in control of the game.
Jose Mourinho talks about the decision to start Andre Schurrle instead of Fernando Torres - We Ain't Got No History
Yeah I don't know why people have a problem with Schurrle starting. Chelsea collapsed when he went off.