Pretty much this. Seen some mad posts about his fitness along the lines of he should be fit by now (even comparing him to Delph after yesterday), but he really doesn't look right. His jump/leap is nowhere near what it was last season.
Maybe he'll never get that back, it really depends just how bad his injury was. Maybe he's just been rushed back and isn't right. Maybe he just hates us and is dreaming of his next photoshoot and being supplied by Sakho at Arsenal.
If nothing else I think having him central allows us to play Richarlison where he's more effective. Really dubious about the play Rondon shouts though. You'd be better playing me and I'm 16 stone and couldn't run a bath, never mind a centre back. Probably lighter than Rondon actually.