ANAHEIM -- For the crew chief handling instant-replay decisions at Angel Stadium, the task will be a relatively easy one.
If a replay is needed on Thursday night in the series opener between the Rangers and the Angels, Dale Scott will take a short trip to an exit a few paces behind the plate, down a short flight of stairs, hang a right in the hallway and a quick left into the umpires' locker room.
Within a couple of steps of the doorway on the right side of the entrance to the room is a locked security box. Inside, the contents are simple: a Sharp 19-inch flat-screen monitor, a remote to turn it on and a hard-wired telephone with a direct line to New York and the instant replay war room at the offices of Major League Baseball Advanced Media.
There, the real work will be done, as a group of technicians will monitor each game and an umpire supervisor will help to identify which feeds are being used if there is a replay request.
Instant replay made its debut on Thursday with the Rangers/Angels series joining the Phillies at the Cubs and Twins at A's on the system's inaugural day. The full rollout will happen on Friday, when all teams are in play. The decision was made to start the availability of replay only at the beginning of a series.
Replay will solely be used for disputed home run calls: whether it is fair or foul, if there was fan interference or if there is a disputed boundary, such as Alex Rodriguez's homer on May 21 at Yankee Stadium that hit a set of yellow stairs beyond the outfield wall and bounced back. That was incorrectly ruled a double after initially being called a home run.
"I think this is just a safety net for game-changing things that can happen if a ball is fair or foul, and there's a limited application where it's worth the application," Angels manager Mike Scioscia said. "But past that, there's going to be no use at all for those kinds of things to change what's going on on the field."
If there is a questionable call, the crew chief will determine whether replay is necessary. If it is deemed so, he and possibly a second umpire will go to the replay setup. There, they will make the call to New York and request the feeds, which will be culled from both the home and away telecasts and possibly the in-house feed.
The crew chief will then make the decision without help beyond technical assistance from the umpire supervisor in New York. That differs from the system utilized by the NHL, which mandates that all calls be made by a central replay official in Toronto.
Once replay is used and a decision is made by the crew chief, the call will be final and managers will not be able to argue further or they will be ejected, not unlike arguing balls and strikes.
"I think there's a value on some plays," Scioscia said. "It has to be a very limited application. I mean, very limited."
Mike Scarr is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.