I don't follow...
Bonner was on the team that gave up 81 points to one player. So that means what about Bonner - that's he's not a defensive stalwart? We all know that.
Bonner is NOT a bad player. Let me repeat that - Bonner is NOT a bad player. He's a role player and a fairly decent one at that. To understand why he plays the minutes he does would mean you understand the Spurs system and the confidence a coach can have in his players.
Does Bonner get too many minutes - yes and no. Some games he does, when he's off. When he's on, he probably should play more. The Spurs are 1st in the NBA in 3pt % at .395. That's 40% from the 3 pt line!!!! Bonner is a part of that and is currently 7th in the league shooting 45%. And as important as the 3 pt shot is to the Spurs success, Bonner is a fairly significant part of that.
From NBA.com, the 2nd best +/- for 5 Spurs players at one time is Duncan, Bonner, Parker, Green and Neal with a score of 24. Bonner is 2nd on the team (behind TP) in individual +/- w/ 167.
I really don't get all the Bonner hate . . . some games he's not very good. In the playoffs, his production wasn't the same. But it's not like he's some 4th string scrub.
Instead of bashing him, watch how well he and the team does when he's in the game and compare that to when he's out of the game.