To an extent that's the case, but that makes no allowance for partnerships learning each others' games. If Williams was to retire at the end of the next qualification campaign, surely it would be better if his replacement had competitive game time with James Chester (assuming he'll then become our main centre back) than if he was thrown in the deep end. Yes, whoever replaces Williams will have to be a good defender to get selected, but when making a strong start to a group campaign is important (something we failed to do this time around), preparation is key.