Understand where you're coming from but the thing is how often can we rest Mata though? Even you pointed out that we need a decent back-up player and it's because we don't have a decent back-up player, we have to play Mata more often than not. And yes, when you look at the bigger picture, Mata has played loads of game but it's not like he doesn't get some rest here and there(thanks to Benitez's rotation!). Unless he plays like 9-10 games in a row, don't see why he should be rested anyway after just 3-4 games etc. Mata is strong enough to handle this issue even though it's tiring.