I would actually love to see Brooks play for a Mike Shanahan, anyone who knows how to put two decent plays back to back on gameday. I still put more of the blame there on coaching. (especially gameday)
I think the rule this year is 'sack Brooks and you automatically get 25% of your sacks for that half.'
Its hard to evaluate a player who spent his career under Haslett and now is failing under one of the worst offensive lines in modern history. Brooks could start at left tackle and the raiders would not be 25% worse.
In the end I think Brooks failing come down to two main things: he was not allowed to run after his first season and he threw passes that lacked the touch and consistency to be consistently catchable (which in turn eroded receivers confidence and leads to even more drops).