There are three ways that a batter can commit batter's interference. He can interfere with the catcher making a throw to retire a runner in the act of stealing a base. Second, he can interfere with a play on a runner stealing home. Sometimes these two overlap. Finally, he can commit backswing interference (also called "weak interference"). This happens when the batter swings and on the followthrough his bat hits the catcher or the catcher's glove. Each of the three case is handled differently so we'll take them one at a time.
1 - Interfere with a catcher's throw
When a base runner is stealing and the catcher comes up quickly with a throw to attempt to retire the runner, the batter cannot in any way impede the catcher's effort – either intentionally or unintentionally. If he does, then the batter is out, the ball is dead, and all runners must return to their time-of-pitch base.
The most common steal-and-throw scenario is a runner stealing second on a pitch (as opposed to a passed ball or wild pitch). Sometimes you see a steal of third, but not very often. So on a steal of second base, you don't often have interference because the catcher has a clear line of sight to second base.
But sometimes you do – for example, when the batter's swing pulls him off balance and he steps onto or across the plate. If there is a runner stealing second when this happens, you can very easily have batter's interference. When stepping over the plate, the batter can easily bump or otherwise impede that catcher's attempt to throw down to second. That's interference.
You can see a good example of this in the video clip. Kendrys Morales strikes out swinging and falls across home plate, causing interference on the catcher, who is attempting to throw down to second. In this case, because the batter has already struck out, it's the runne, not the batter, who is called out for the batter's interference.
Copyright © Major League Baseball. By permission.
We said a moment ago that most of the time the steal is of second base. But not always. Sometimes you get a base runner stealing third, and this is the case where you really need to watch for batter's interference. That's because the throw to third often requires the catcher to throw across the right-handed batter's box. And that's where the batter is standing (if he's right-handed). And you can't expect the batter to simply disappear.
Now, this gets a little bit tricky. There is a common misconception that if a batter remains in the batter's box he cannot be called out for interference. This is not true. The batter's box is not a safe haven. But, as we said, he can't be expected to disappear, either. Add to this that a play on a steal of third happens so friggin' fast that the batter may not even know a play is on until the ball goes whizzing by.
And let's not forget about snap throws down to first base to catch a runner leading off too aggressively, or who may not be paying attention (yep, sometimes they catch runners sleeping). You have the same issue here as you do with throws to third, but instead it's with left-handed batters.
So, with all of this fuzzy grey zone, what's an umpire to do? Well, the wording of 6.03(a)(3) is important here: The batter is out if he "… interferes with the catcher's fielding or throwing by stepping out of the batter's box or making any other movement that hinders the catcher's play at home base." As directives go, you can't get much broader than "any other movement." Batter beware.
The emphasis is important because "any other movement" covers a lot of ground. A lot. So the message is, give the balance of judgment to the catcher. Sometimes a bad throw is just a bad throw and you have nothing. But if the catcher's throw gets disrupted in any way, regardless of intent, you've got to call it.
And the thing is, you have to learn to see it. Especially on the lightening-fast throws to third. If it were just about contact, or intentionality, the call would be easy. But it's not an easy call because you have to account for (let's say it again) "any other movement," and you can't explain that part in writing. It's field work. Like I say, you have to learn to see it.
But again (for the third time), you can't expect the batter to simply disappear. You have to watch and judge for yourself whether the batter made "any other movement" that hindered the catcher in any way. This is a judgment call, of course. Generally (generally), if the batter remains still in the batter's box and makes no movement, then he is protected from interference. If it were me, though, I'd duck. But that's just me.
Here's where it gets even more tricky
The batter's interference play that I belive causes the most arguments is not on a straight-up steal. Instead, it's when the catcher mishandles a pitch (or is handling a wild pitch) with runner on base. The ball is on the ground and runners are in motions and the catcher is diving or grabbing for the ball; at the same time the batter is dancing out of the way while trying to avoid interfering, and in doing so he instead interferes. That's interference. "But I was trying to get out of the way," the batter protests. You're breaking my heart, son. You're out.
2 - Interfere with a play at the plate
When a runner attempts to steal home, the batter has to make an effort to get out of the way of the play at the plate. This can be tricky if the runner is stealing on the pitch, as with a suicide squeeze (which is rare, but it does happen). A play like this happens very quickly and even you, the umpire, probably don't realize what's happening until split seconds before it blows up right in front of you.
More commonly, this happens when there is a runner on third (R3) and then there's a passed ball or wild pitch and R3 tries to score. You have the catcher scrambling for the ball, the pitcher running in to cover the plate, and R3 barrelling home. Get position and watch like a hawk.
There's a similar situation when there's a sacrificial double-steal. That is, with fewer than two outs and with runners on first and third (R1 and R3), R1 will sacrifice himself on an attempt to steal second just to draw the throw so that R3 can then steal home. You don't see this too much at higher levels (16U and above) because the fielders are good enough to defeat the play with fast, accurate throws. But at younger levels you see this all the time. Again, watch this one carefully and don't be fooled by the defensive ploy to fake the throw to second and instead hit a cutoff fielder who then makes a play on R3.
3 - Backswing interference
When a batter swings at a pitch and the momentum of his swing brings the bat around and hits the catcher, or more commonly, the catcher's mitt, this is backswing interference. It's sometimes referred to as "weak interference." When backswing interference happens, you must kill the ball ("Time!") and return runners (if any are in motion) to their time-of-pitch base. However, no one is called out.
Rules Variation: High school (NFHS) rules differ on this point. NHFS rule 7-3-5c penalizes backswing interference when it interferes with a catcher's attempt to retire a base runner. The batter is declared out, the ball is dead, and the base runner must return.