I listened to Locke for once and got a little worried- I'm not sure Whiteside is effective at 15 minutes a game. He's been most effective at 30 minutes. He obviously wont be playing 30 minutes a game for the jazz, but hopefully he can be effective at around 20. I don't think Rudy plays over 30, he's settled in pretty good.
The issue is his effort level. He got paid a big contract in Miami and has been coasting for a few years. However, with the Jazz being a legit contender, the hope is that he'll play hard. Playing backup for the Kings wasn't going to motivate him.
Jazz can play Gay or Dok at the 5 if Whiteside doesn't pan out.