I just think Gabe gives them a little more in terms of PG play.
For example, when TA throws the ball into the post, it seems like a 50-50 shot at best. If Gabe is doing it, I'm much more confident.
2nd if its a pass into the post, the defender is leaving TA who isn't a 3 point threat, if Gabe passes the ball in, then, the help defender is less likely to leave him.
Here's the rotation I think would work best, again depending on matchup.
Shooter, shooter, slasher, big, big
1st sub/lineup House, Gabe, Pierce, Baby/Powe, Perk
2nd sub/lineup Rondo, Allen, TA, KG, Baby/Powe
I realize most of the lineups are a tough matchup, but last night, Pierce played Kobe most of the night, and Ray was on Walton or Sasha. I think Gabe can play in that spot, puts more pressure on the defense