What really happens in the MLB replay review room?

Raj Mehta-USA TODAY Sports

NEW YORK -- In a square midsize room above a popular Manhattan eatery, the fate of a playoff baseball game -- or even an entire series -- could be determined. Major League Baseball's video review room -- used for manager challenges and umpire crew-chief reviews -- is a big part of baseball all season, but especially so in September and October.

But what do we know of what goes on in that room?

On a recent quiet afternoon in New York, ESPN.com was allowed access. Per MLB rules, it was given only before the first game of the day began. Video reviews are such a large part of baseball now, we sought to get some answers about a process that could loom large at any time over the tension-filled nights of late September and October.

How is the room set up?

There are six stations with an umpire assigned to each, depending on how many games are going on. Each station has two televisions, so each umpire is watching up to two games at once during the regular season. Next to each umpire is a technician who can control the replays as they come in from the TV trucks on-site. An umpire supervisor is on hand as well.

So what happens on a close play that might be challenged?

The umpire at that station immediately begins to give second and third looks at the play as the replays come in from the trucks on-site. Even before the umps in the stadium have put on the headset, the ones in New York have already been looking at the play. Once a play is officially challenged, the other umpires in the room, as well the supervisor, can gather around the umpire who has been watching that game and advise him as they watch replays of the play. The replay tech will have any number of angles to show the umpires and can sync up two shots at once.

When it comes time to make a call -- hopefully within two minutes -- final say comes from the one umpire who has that game.

Do the umpires on-site and the replay umps in New York communicate about the call?

Not really. Once a call goes to replay, it is up to the replay official to make the call, and the umpires at the stadium where the play took place are not involved in that process.

How many reviews does each umpire at a station average per night?

Believe it or not, there are only 0.5 reviews per game, so if an umpire is watching two games, he'll average about one review per night. Obviously, that can vary, but the average is one review for every two games.

What are some of the hardest calls to make even with review?

In general, video review teams cite three calls as most difficult: hit by pitch, fair/foul home run calls on balls that go higher than the foul pole, and tag plays at second base.

Hit-by-pitch calls: These can be difficult for obvious reasons: Did the ball hit the bat or part of the hand, or both? If so, which did it hit first? Often, a ball will careen one way or another, indicating it must have hit the bat, but that doesn't mean it didn't touch a hand or finger first. Slow-motion replays usually can tell the story, but it can still be a difficult call: bat or hand?

Fair/foul over the pole: These aren't fun and take a lot of back-and-forth with the mouse. At the end of the day, review or not, it's still a judgment call.

Tag plays at second: One simple reason second base stands out over the other bags is because of where the cameras are in relation to the field. First, third and home are closer to the stands, so they often have cameras very nearby -- with better replay looks. Second base is also where overslides and pop-up slides happen the most, sometimes allowing for minuscule room for a tag.

Does a tie really go to a runner?

First, yes, there are ties. But instead of automatically going to the runner, the call simply reverts back to whatever the call on the field was. Ties will elicit a "call stands" notation.

What else might surprise fans?

One thing fans might not know, especially on close plays at first base, is that the ball is considered in the fielder's glove as soon as it touches any part of the leather -- it doesn't have to be in the pocket with the glove closed. So if the replay shows the ball touching leather before the runner touches the bag, and before the ball is actually caught, then the runner is out. Of course, the catch has to be completed.