The player can demand to renegotiate all he wants - the team is under no obligation to do a thing. The team agrees to renegotiate only when it's in the team's best interest to do so. If they refuse, the player's option is to sit out and default on his obligation and get paid ZERO until the contract expires.
Right, they pay when the contract requires it, and pay zero when the contract doesn't. For most players, that means if they signed a "$1 million" contract for that year, and they blow out their knee game 1, career ending, they'll be summarily released Monday morning, nothing more due under the contract than the 1/16th they earned through Sunday's game. Stars demand and GET better deals. It's negotiated. It's business.
We're not - both sides are being held to the terms of the contract, nothing more or less.
Of course that's my position because if they can avoid paying the last few years, they will. And if the contract is guaranteed, limited only by the financial ability of the team to make good on the amount, the player will sue and win the balance due, maybe plus attorney's fees, maybe plus punitive damages. If the team thinks it can win that lawsuit, say they suspect the player hid an injury and the contract allows for default in the case of player misrepresentations, it will default and go to court. Morals enter into the decisions NOWHERE in the process on either side.
Of course he has to honor his contract - he has no other option. He can try to negotiate a pay raise, and if that fails he has a choice, like we all do in our jobs. We can work for the amount agreed to, or quit. In the NFL, that means he can't sign with another NFL team and sits at home playing video games collecting no pay, but he has that choice like you have that choice and any high profile CEO for a Fortune 500 has that choice.
Nope. See above.