Game 1, I'll give you, that was Big Baby's worst game. However, Glenn Davis was a HUGE reason why the Celts won Game 2, with his hustle plays and making a couple of HUGE shots towards the end of the game.
Game 2 he made his last shot with 9 and a half minutes left in the game. He didn't even play the last 6 minutes of the game. Yes he made some hustle plays early in the fourth but the C's didn't take that game over until after Davis was on the bench. I'll give you games 3 and 4 as Davis played well both games but he tends to disappear on the road. Not a knock against him, bench players notoriously play better at home. He definitely hustles every possession but his game 2 impact wasn't as big as you think.
But, I agree with your other statement 100%. As good as Davis and Robinson is, they're not good enough to beat the Lakers. However, the bigs for the Celtics, with help from guys like Davis and Robinson, most certainly are. It's key for them to start hitting as a unit, instead of as individuals.
Game 5 is a must win for them. Honestly I think game 6 is almost a must win as well. I don't see them beating Kobe and the Lakers on the road in a game 7.