Acting like an ass is a time honored baseball tradition. George Brett was a notorious "red ass". As were Kevin Brown,Paul O'Neil,Kevin Youkilis, Hal McRae, Lou Piniella, Earl Weaver, Bobby Cox and the list goes on and on. There is a huge difference between acting like a jerk on the field/dugout/locker room and acting like an ass in real life.
Harper, like most of us, doesn't carry the jerk-off mentality into his off field behavior. So he is exactly like all of the other "adult" members of society.