It's rare for a player to make it so late in his career so he's a bit of an unknown quality, I doubt he'll have another season quite that good again but he is a goal scorer and we could do with one.
We don't need him if he can't manage more than 24 goals in all comps. It's the same amount Giroud scored but we also had cup games to play. He has to be able to have a bigger season than what he had with Leicester otherwise it's a pointless move.