Generally true, but exceptions to every rule. Cerv was obviously one exception.
Gates Brown of the 1968 World Series champion Detroit Tigers was another. In a year when batters managed to hit .230 overall, when Pete Rose won a batting crown at .301, Brown managed a .370 batting average and a .442 OBP in less than 100 at bats. In addition to being an awesome bat off the bench, Brown was a character who is best remembered for hitting a stand up double with two hot dogs stuffed in his jersey.