Both times the bloodbender only lost because either

1. Opponent was the avatar

2. Got overconfident in their abilities

If u had a smart and to the point bloodbender they could probably do a lot of damage.

Like Yakone, he knocked a whole courtroom unconscious with his mind, he lost because Aang ent into the Avatar state. Honestly, I think the Air ball is a little overrated, sense we see Aang move at the same speed, if not faster, then when he was on his Air ball.

Flight, honestly. People say it's such an advantage in fights, but really any decent earth- or waterbender can shoot projectiles at the person in flight, and solid firebenders can use jet propulsion to take them down. It really doesn't help.