The flip side is also true in that Doc will let veterans play on when their production or even effort is poor or erratic. Look at 'Sheed a couple years ago or how consistantly atrocious 'Quis had to be this year before Doc consigned him to the bench.
Mike
Players' form varies. It doesn't make any sense to shut down a player with a record of producing because of a bad moment of form. Especially if you don't have anyone good and reliable to play in front of them.
Maybe the young players behind them are scrubs, or maybe not. But how do we ever find out unless Doc plays them enough in real games for them to demonstrate some NBA level skills?
If you were a NBA coach and you were seeing that a guy in practice was a scrub or totally unready to play in the NBA, would your thought process go "okay, I need to play this guy because some fans like to see young players on the court with their own eyes"? Do you think Popovich should have played all those guys I mentioned more or it's just Doc? Because, again, Doc isn't unique - this complaint about coaches not playing young players enough is very widespread. It's mostly because fans want to see them because there's always the hope some of them may be a next big thing or at least a good player.
Plus, playing time doesn't help all young players and can actually hurt some. To some players, it'll only mean they'll be acquiring bad habits or getting their confidence shattered. Not every young player is ready to benefit from more playing time.
Not the case of the recent Celtics youngsters that didn't get playing time though. They were just bad. I for one am glad I wasn't forced to watch Patrick O'Bryant, Luke Harangody or Lester Hudson more than the strictly necessary.