Apparently you've never heard of using positive reinforcement as a motivational tool... I'm sure Dice took heart with his performance today, just as I'm sure he was down about his performance against the Rays, but that doesn't mean it wouldn't have helped him to walk off the field to resounding applause for a job well done.
If it was Lester or Beckett throwing a gem like that I'd feel the same... when you throw the ball that well, you deserve to hear the praise from the crowd. Letting him pitch the 8th was a no brainer, especially with his pitch count at that point. He was dominating the Jays and he could have handled them just fine had he gone back out.