John Lackey slings a slider, and it ducks under Pablo Sandoval’s front kneecap and darts past the inside edge of home plate.

The animated graphic on TV shows the ball barely touching the box.

OK, Mr. Umpire: Ball or strike?

The strike zone is getting plenty of attention this postseason. And with no replays allowed, ball-strike calls are sparking all sorts of disputes.

Lorenzo Cain of the Royals got flustered when Tim Timmons rang him up. Matt Kemp of the Dodgers sounded off after Dale Scott called him out. Asdrubal Cabrera of the Nationals slammed his bat and helmet and was ejected by Vic Carapazza.

“We don’t have the box out there when we’re pitching,” Kansas City left-hander Danny Duffy said. “These umps are in ‘The Show’ for a reason. Everyone’s got a pretty good idea of the zone, and I’m sure the umpire behind the plate has a better idea than we do.

“You just try to throw wherever you think the zone is,” he said.

Twenty years ago, several veteran umpires were known to have their own definition of the strike zone. Some were low-ball umps, others called higher strikes.

A decade ago, there was this thought: Take away pitches above the belt and below the knee, but add a little extra on the outside corner, a spot where hitters could still make contact.

These days, when Major League Baseball grades every pitch and often gives umpires a report 12 hours after their plate jobs, strike zones have become much more consistent.

Not that there haven’t been disputes. Since replay rulings can’t be argued, some managers have blown off steam squawking about pitches.

The rule book says it’s a pitch where “any part of the ball passes through any part of the strike zone.”

There are some umpires, however, who look for a little more. Say, half the ball in the zone for the half the time it crosses the plate — 17 inches wide, 17 inches deep.

Now, try pinpointing Yordano Ventura’s 100 mph heater or Tim Hudson’s dipping sinker in less than a half-second.

“That’s just the human element of the game. You’ve got to find out where it is,” Baltimore reliever Tommy Hunter said. “You have to judge how much the umpire is going to give you up and down, inside and outside,” he said.

As for that TV box, well, it all depends.

“That’s accurate to a point, but some guys are 6-6 and others are 5-10. They’re not going to have the same strike zone, but on TV, it’s the same strike zone,” Hunter said.

For all the sophisticated cameras and advanced math used to project a zone, there’s another key element: the catcher.

How a catcher frames a pitch can make all the difference. If he’s too obvious in trying to pull his glove in a couple of inches, he might convince an umpire that it was too wide. If he keeps his glove steady, it’ll look like the pitcher hit his target and is more likely to result in a called strike.

“I think it’s as accurate as it can be,” Royals slugger Billy Butler said. “It’s not 100 percent accurate, but the strike zone is a hard thing to judge.”