Mo is obviously a very talented player, but I wonder if his strengths are not really relevant for us at the moment. Playing in a confident team which has the majority of possession, he will look classy and metronomic, but that's just not us right now.
He's never offered us a massive goal or assist threat, and I'm just not sure what he does bring at the moment. Even last season I wanted him to have a bigger direct impact on games, rather than "keeping us ticking over".
If Mario was fit, I'd want to see him in there, as he can add a bit more attacking momentum.