I get both sides of the argument. There is a very good chance he ends up as a semi-effective role player on a regular team, just as he is now. But, there is also a chance that he ends up actually increasing his production with increased minutes (as LarBrd33 nicely laid out). That 'chance' is why he'll get a decent contract offer next season.
Potential is the key to the NBA - we sit and wonder why guys like Bass and B Wright can't fetch a first round pick even though it is extremely likely they will be more productive than the late 20s pick they would be traded for. For veterans, they are already a known quantity, but that pick could be the next Gasol/Jordan/Parsons, etc...clearly better than Bass or Wright.