re: If JaMarcus wouldn't have held out, would his NFL career be different?

Not at all... He was what he was. No need to discuss an alternate outcome. Now if the question was, if he went to a team with better front office personnel and vets that could have made a difference, thats a different scenario, but I still say he would of flamed-out even playing for Bellicheck and the Pats...
He got the money and lived life... It is what it is. Im sure he has as much regret for not putting in the effort as much as we say he wasted his talent and opportunities.