I look at their piloting as being similar to drunk driving. While drunk drivers have a much greater probablility of being in an accident, most do make it home safely. Probably there are tons of accidents and botched landings in the reaver fleet, but they can still keep it sort of together and most ships can go where they want.
Also, I agree that the reavers bloodlust is periodic and is fixated on non-reavers. Kind of like an exaggerated version of the way humans will commit atrocities against outsiders but will be moral and polite to members of the tribe. Also it grows in direct proportion to the proximity of non-reavers and to the amount of reavers in the mob. And the longer it takes them to get their pray the more frustrated and enraged they become, eventually changing from people who can more or less fly spaceships to mindless zombie hordes.
Looking up I notice Ex-Tank has made similar comments, but I’m posting anyway. 