As far as the Carwin/JDS thing goes... How did he show he was human against Roy? By failing to KO him? That dude has a chin that's quite possibly better than Mark Hunt's was. I do not understand how he can take as much punishment as he does in all honesty. Your other points are valid though, but you also have to remember that Carwin has yet to face a striker anywhere NEAR the level JDS is on as well. As far as Junior stuffing him, I'm not sure it will happen either, Carwin is a big dude with a powerful shot, but he's also sluggish on his feet and I expect JDS to be constantly active from the bottom if he ends up there. But yeah, your point is entirely valid, that fight is one fight I'm very uneasy about calling a definitive winner, it could really go either way.
JDS had a decent reach advantage on Nelson. He could use his mobility and angles to keep Roy off him and maintain a distance where he could hit Roy but Roys arms wouldnt be long enough to hit him.
Carwin is the opposite. He has reach on JDS. JDS will need to come forward to get inside Carwins range. JDS may not have the distance he enjoyed against smaller fighters like Roy that he can utilize to make himself look pretty. JDS needing to get inside sets him up nicely for a shot even if Carwin enjoys plodding moreso than exploding forwards.
Carwin also seems to have excellent accuracy and timing with his punches even if his mobility has never really been displayed I think Carwin can move much faster when he needs to.
Thats how I see it, anyway.