From watching his games, I don't think the characterization of him as an inside footballer is that true in that he rarely gets the hard ball himself. Instead he's more of a conduit from that into the spread, and more often gets his ball very outside thanks to his running ability. Probably a bit like Redden in that they seem like they should be an inside player but aren't really that effective there. Redden has better disposal, Bell has better running.
I don't quite agree. I think you've accurately described his 2015 but I think that his style has been driven by the role he is expected to play, rather than what he is capable of. When he's gone into a stoppage as a ball winner, my impression is that he is pretty successful at winning or negating the contest.
The issue for Carlton has been that they have had to fit a few "inside" types into their best 22, alongside Murphy and Gibbs. Cripps has obviously become the #1 guy in terms of that ball winning mid role. You then have Curnow who is hard bodied, has a big engine (albeit he plays a more defensive role) and isn't highly skilled. Carazzo is a bit similar, albeit probably a bit more outside. They got games into Holman who is an inside mid too.
Because of his versatility, Bell didn't really get the game time at the coalface to really show his true capability in terms of contested footy. I think he's capable of playing as a big bodied mid and would be quite successful in a similar role to what Robbo played late this year.
The question in my mind is whether Bell is a player of need with the rise of Robinson, the likely development of Robertson, the plethora of forward flankers we seem to have, and the fact that Lester is still on the list. I personally think Bell is an upgrade on Lester but I wasn't convinced the best 22 had Lester in it.
What you do get with Bell is a player who is "ready to go", can play multiple roles in the best 22 and brings a couple of really good attributes that are somewhat missing from our side (really strong body and the ability to run all day). We'd have a stronger squad with him in it, depending on what we'd have to give up.
In theory, I'd go Casboult + Bell for Aish. However, I'm sure Carlton supporters would hope for more, particularly if Aish nominates Carlton as his preferred destination.