I agree to a point. The problem with his matches with Bobby Lashley and Khali are that John Cena has more in-ring skill and experience than them but that actually counters my statement where he can't really carry another opponent in a match. Those were some good matches that he was able to have with them. For example, with The Rock at Wrestlemania XXVIII, he carried The Rock through that match which wasn't exactly that bad of a match, not the best but not bad.
I don't feel any match can be great if any WWE Superstar carries the other. It's a great match because both, or all, of the WWE Superstars competed together with perfect in-ring chemistry and worked really well with each other.
I wouldn't say great matches but I think CM Punk working with Ryback quite a bit before Hell in a Cell 2012 was really helpful. It wasn't a great match but at least Ryback didn't look terrible. Most likely because I set him at a very low bar before the pay-per-view so anything was considered an improvement. I think Alex brought this up but he worked really well with Mark Henry during a few Monday Night Raw matches.