To elaborate on what I said earlier, reading it back I don't think I made my point very clearly. I think the Packers should stick with Brooks because he has the potential to be one of the best punters in the league (just as the Packers stuck with Crosby because he had the potential to be one of the best kickers). When Brooks was in college he was touted as the best punter since Shane Lechler. Kapinos is unlikely to improve any further, he's two years out of college and he doesn't possess the naturally strong leg that Brooks appears to have.
In training camp even though Brooks has shanked the odd one, and apparently is suffering from a hip-flexor, he still has better numbers than Kapinos. In addition, Brooks is also a good holder. I can't find the statistics on this, but I'm pretty sure Brooks has out-performed Kapinos in the pooch-drills in camp (pinning the opponent inside the 20.)
The Packers gave up too early on Jon Ryan even though he had all the tools to be a top punter. Instead they went for - what they thought - was the steadier option, however Derrick Frost was just awful. I hope they don't give up on Brooks.