I'll try and take each bit of it as it comes.
Gana is miles miles better than Chambers mate. His numbers at what he does are still elite. There were some stats recently around ball recovery and retention, and hes Rodri-esque in terms of PL midfielders. He has limitations, but at doing what you want an DM to do he remains elite. He is nowhere near Gana level.
As for a back up player, presumably we would have to pay a fee? Plus 50k p/w. This works out pretty expensive. Like the fee isnt going to be a few hundred thousand is it, you are definitely going to want a couple of million at least? It is a lot of cash for a guy who is just going into the squad (at best).
We need to sort the financial side of things, by buying younger players, on lower wages, who gain value. Is Chambers going to do that, at age 28, when he isnt good enough to get into the team?
Like I me it nicely but for most of last season you were as bad as us, and he couldnt get near your team. He played 2 games for you. If hes not good enough for you, hes not going to be good enough for us either, and at 28 hes never going to be good enough. If he was a decent PL player he would be getting games.
It would be like me pitching you to sign Michael Keane. It would just be a stupid move for Aston Villa.