I'm probably missing some esoteric joke here, but I'll play dumb and note that humidity isn't really a 'test' for knuckleballers, it's simply a meteorological fact. The air is less dense, has less resistance, and consequently a knuckleball moves less (curveballs likely have less action as well). Also, contrary to what is generally assumed, hit balls should travel farther. Most commentators claim balls don't travel as well--if they're right (and maybe they are, since I don't know whether it's been tested), it's the result of factors other than air density, which is the one they usually cite (do the balls absorb moisture? does the covering get less resistant?)