Disagree. Lakers have Luke Walton on an even bigger contract, yet are NBA Champions. Challenging the Lakers doesn't have anything to do with Bonner, he's a serviceable bench big, that's it. A playoff scrub, if you want, fair enough, but he's had a very decent career - 6 seasons, 430 games played, 7 PPG, over 40% career 3-point shooting. He's a legit NBA bench player. No more, no less. This is why his contract numbers are more in line with Yohan Petro's than Pau Gasol's.
Him being on the Spurs roster has nothing to do with the Spurs 2010/2011 championship chances, none at all. Just like Mahinmi.