Our problem is that we've often played with a slow/static midfield (James, Sigudsson, Gomes - occasionally all at the same time ), and to ensure you don't have chasms of space between the defence and midfield you have to push the defence up closer to that midfield (or pull the midfield back, which is what Ancelotti did, but it makes you anaemic further forward as all you then do is move the gap to a different part of the field). And, of course, if you push the defence higher up then they need to have pace so they don't get caught in behind (a more mobile central midfielder would also help, but a more mobile central midfielder AND a more mobile centre back would make a huge difference at both ends of the field tbh).
Godfrey has pace in spades. Holgate isn't super fast but he keeps up (which is why Ancelotti had wanted to pair him and Godfrey). Mina is about average pace. Keane is slow, but - as we saw against Leeds - he's also not 'mobile' (so he's prone to getting turned/caught down his sides).
Great attitude, seemingly great guy, very professional, has definite attributes. But the problems he has are physical ones that can't be retrained/improved.