Although the stats on that front do exaggerate their problem (the first games with the new manager, and then away to Everton), it is indeed a problem for them, and they should have worked harder to have a backup for him.But look what happens to palace when Zahahahaha isn't available.
It certainly should be easier for us to cover for a centre back than Palace for Zaha, but the basic point of not having to lose good players straight away stands.Yet the Albion shipping out a centre half for mega money just means the next one plays and nobody notices the difference.