EXPLAINER: What exactly is a check-swing?

SAN FRANCISCO (AP) — It’s always been one of the most murky areas in baseball: What exactly constitutes a check-swing?

Suffice to say, a lot of people were taking a swing at that one Thursday night after San Francisco's Wilmer Flores was ruled out on precisely that kind of call, ending the Giants' 2-1 loss to the Los Angeles Dodgers in the deciding Game 5 of their NL Division Series.

A hotly disputed call, too.

So how far does a big league hitter have to go with his swing in order for a pitch to be called a strike? Is it when he “breaks his wrists” trying to hold up? Or when his bat crosses the plate? Or when he appears to be trying to hit the ball?

Don't bother looking for it in the Official Baseball Rules: Amazingly, in the nearly 200 pages that govern Major League Baseball, there's no mention of how to decide.

Officially, it’s purely an umpire’s judgment.

With a runner on first base and two outs in the bottom of the ninth inning, Flores appeared on TV replays to hold up on a low-and-away slider from Dodgers ace Max Scherzer on an 0-2 pitch that missed the strike zone.

Home plate umpire Doug Eddings checked with Gabe Morales at first base — umps at first and third often have a better vantage point on check-swings, and plate umpires routinely ask for their help on such calls.

In Morales' judgment, Flores swung. Morales raised his right arm for strike three, and the highly anticipated playoff game ended with a whimper.

By rule, judgment calls are not reviewable under Major League Baseball replay rules and there's not been any movement to change that. Some angry fans at Oracle Park tossed pieces of trash onto the outfield grass.

“Check-swings are one of the hardest calls we have. I don’t have the benefit of multiple camera angles when I’m watching it live. When it...

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