It really is amazing what happens when Devin Harris is on the floor compared to the stretches when he's on the bench. The offense comes alive, more players are open, Mavs are coming off of screens and everything looks natural.
Concerning backups, JJ Barea is fast, but doesn't have the body control or the respect of defenses and in turn, doesn't spread defenses thin like Harris does. He can also be a defensive liability when paired with taller point guards. He also hasn't learned how to convert quickly when he has the ball in the lane and often gets his shot blocked or commits a turnover when running among the trees.
When Terry is running the point...well, the ball moves around and someone takes a jump shot. Suffice it to say that even though Dirk may be the Mavericks' best player, Josh Howard is developing into a star and Jason Terry is an excellent scorer, Devin Harris is the grease that keeps this machine running and without him, the Mavericks would be in big trouble offensively and defensively. The Mavericks were without him in their last meeting against the Trail Blazers, and limped into the half with a 49-42 deficit. Things didn't get any better and the Mavs eventually lost 91-82―their lowest scoring game of the season. With Harris in this game, the Mavs have sped to a 44-36 lead at the half and are looking positive heading into the locker room.