Expanded instant replay is officially coming to Major League Baseball in 2014, with the league announcing that the new system received approval from all 30 clubs.
Under the expanded system, managers will be allowed to challenge a number of different calls. The list, per the league's release:
- Home run
- Ground rule double
- Fan interference
- Stadium boundary calls (e.g., fielder into stands, ball into stands triggering dead ball)
- Force play (except the fielder's touching of second base on a double play)
- Tag play (including steals and pickoffs)
- Fair/foul in outfield only
- Trap play in outfield only
- Batter hit by pitch
- Timing play (whether a runner scores before a third out)
- Touching a base (requires appeal)
- Passing runners
- Record keeping (Ball-strike count to a batter, outs, score, and substitutions)
Any manager who successfully challenges a call will be allowed one more challenge to use. Even successfully challenging another call will not earn them a third, though the crew chief can choose to review calls even after a manager is out of challenges. The good news is that managers shouldn't be missing on many challenges, as they will be able to communicate with personnel in the Clubhouse with access to the same replays that the umpires will see.
It's not a perfect system. We'll still have to deal with the oft-questionable strike zones, and the fact that a manager could get two challenges right and then miss out if a particular umpiring crew manages to make three mistakes in the opposing team's favor seems...questionable at best.
But for better than a century baseball has simply ignored the fallibility of umpiring crews, passing it all off as some sort of desirable "human element" when alternatives were readily available and already implemented in other leagues. Even an imperfect system is a huge step in the right direction.