Brooks has good mechanics and throws a good ball. He is a good athlete as well. The problems with him aren't physical. Like most guys that make it to the NFL, they have the physical abilities, it is the other stuff that makes you good.
Brooks lacks pocket awareness. That is why he gets sacked a lot. He continues to make impulsive plays, which the majority of the time lead to turnovers. He isn't horrible, but it does not look like he will be any better than he is right now. I think he would be a good back up although I doubt he would accept that role.