I was as big a Cam fan as there was from 2010 to his NFL MVP season. However, I think the injuries (which have Shirley hampered his abilities the last couple of years) are largely a smokescreen for some alarming behavior to the executives. While I would never claim 100% accurate insight into a person's desire or will to succeed in anything, it just LOOKS like when he got beaten down, or when adversity hit, his reactions were not great. He tended to sulk, loaf, sandbag, and appear as though he weren't really connected to the team or playing with max effort. When they were hitting on all cylinders, he was the life of the party and a kid in a candy shop, but when they weren't, he just didn't give good body language.
And then, he comes out of the locker room looking like a doofus pimp half the time. This is what I think happened:
1. Cam gets to the NFL, gets paid, and skyrockets due to his novel physical tools.
2. He ascends in stardom, but soon begins to see himself as a transcendant icon of American culture, rather than just a star NFL player. Hence, the "fashion line" at Belk and all the goofy clothing for press conferences, etc. (Don't get me wrong, I think he uses he public persona/celebrity status for much good in his charitable foundations as well.)
3. His career (likely) climaxes in the Super Bowl season, but the Broncos bring the wood, and in the 2nd half of that game, as he was running for his life most of the game, he basically throws in the towel. The Panthers lose the Super Bowl, and he shifts his focus more on building the "Cam" brand rather than climbing back to the Mt. Olympus of NFL glory (getting back to the SB).
4. Defenses all over the NFL are determined to get Cam injured b/c he acts (in their minds) like an arrogant boor on the field. (I remember watching Cam play in his first Pro Bowl. Every defensive player against him on that field was flying around acting like their careers depended on knocking him on his a$$ HARD. And there is obviously a normal "understanding" amongst Pro Bowlers that the defenders are out there essentially to just get some cardio in. Yeah, they pursue and tackle, but there is nowhere near max effort in the PB. But there was max effort in the PB against Newton, bc of his antics.) They cheap-shot him, hit him late, and essentially "get after him" big-time in games vs. the Panthers. This results in a marginally increased chance of injury, which he succumbs to in the past couple of years (shoulder, foot...).
5. After not having a healthy, committed Cam for almost 2 years, the Panthers execs decide to cut him because any equity he might have built in the minds of the brass is essentially negated by his sometimes lack of hustle, defeated attitude, poor body language, and probably 1,000 other "little" things that have not been publicized.