In Little League, there's a widespread rule that if you throw your bat, you're out of the game. It doesn't matter what you were aiming at, what you hit, or any of that jazz. You throw, you're gone.
When I was ten, I thought this rule was stupid. Twelve years older and wiser, now I understand why it exists. To not have this rule is like assigning a bigger penalty for murder than attempted murder. Why should someone be rewarded just because his shot missed the victim's heart by a few inches?
If you saw tonight's Twins/White Sox game, you probably know why I'm writing this. Jim Thome lost his grip on his bat on the first pitch of a plate appearance, sending the bat flying. Apparently he learned nothing from this, as two pitches later, he lost the bat again, this time injuring Twins catcher Mike Redmond (remember him?) and the home plate ump.
I'm not sure punishing Thome is the right move, as this was clearly an accident, but it makes sense to me that if a player loses his grip on a bat, he should be required to either get a new bat or add some pine tar to the current one. This injury was a fluke, but we see plenty of bats get thrown into the stands every year. Fans down the baselines are prepared for line drives coming at them, but not for flying bats.
If a player loses his grip on a bat once, it greatly increases the probability he will lose his grip again later. MLB needs to do whatever it can to cut down on the injuries that result from these instances. This rule would be a good start.