Again the drive to oust Brady is due in part to his support of gay marriage. There are more than a few social conservatives who take issue with that. However I'm sure some are upset with him over the shellacking the party took in last year's elections.
All the same here's Rich Miller's conclusions:
More Republicans ought to follow Roskam’s lead. These endless fights over an essentially powerless and meaningless party chairmanship, particularly when a hot-button issue like gay marriage is tossed into the mix, are nothing but counterproductive.As I've often liked to state, I don't buy into this RINO nonsense and I don't even know what it's supposed to mean. And it does no good if those "pure" Republicans aren't able to win an election. Core values are fine, but if you want to remain pure then you're not cut out for politics.
Too many Republicans believe that their real enemies are within their own party. Keep it up and y’all will be fighting over absolutely nothing.