Mate I think you've got a skewed view of reality. I doubt anybody would consider Mowen, Dennis or Higgers to be dominant this year.
The bloke has had a number of injuries. It's unrealistic to expect him to just magically be at his best. Are you an active person? Do you actually realise how much an injury affects you when you are at a high level of fitness like James would have been at his best? Can you really understand how much 3 major lower body injuries over the course of 4 seasons would really affect the bloke? Consider the fact that last year he played, got injured, as soon as he was fit he was back in the team, then on tour, constantly picking up niggles and not healing further, whilst playing on the EOYT. In addition, he didn't have the opportunity to bring his fitness base back up. Modern sport does not allow for that, he would have been just trying to keep up.
Then he gets 1 month break finally and he's back into it again and playing within a few weeks. He's done fucking amazingly well to be back improving as the year went on.
You're getting completely carried away. Nobody is saying keep blokes that are past it when there are better options. People are saying keep one who has been the heart and soul of the team, who has been injury affected and has scope to improve further from where he is, and is still in his peak age as a player because there simply isn't somebody better than he currently is to replace him.
You are not holding him to the standard of needing to be better than his replacement, you are holding him to where you perceive he would be.
Let me ask you this. What benefit do the Reds get if we get rid of James because he's not playing as good as we think he can or has, to replace him with a player who is playing at their absolute best if they are not playing better than James currently is anyway?