One of the hallmarks of union activity is resisting capital for labor substitution. To keep wages high, it's important to limit the ability of employers to substitute one resource for another resource. The UAW does this. The MLB players' union did this in the 1994-1995 strike when it fought the use of replacement players and the MLB umpires' union has done this in its fight against instant replay.
Of course, another hallmark of union activity is that unions, in trying to obtain higher rates of pay for their members, are actually one of the driving forces behind capital for labor substitution. Firms naturally try to use the most efficient resource mix to produce its goods, and artificially raising wage rates drives employers to seek lower cost substitute resources. So the union activity is a double-edged sword in this regard.
But that's beside the point. You no doubt know that Armando Galarraga had a perfect game taken away from him by a bad call made by umpire Jim Joyce on what should have been the 27th out of the game. Replays clearly show that the batter, Jason Donald, was out on the play, and it was not even close. You could tell by the reaction of Donald that even he knew Joyce screwed up in a big way. But to his credit, Joyce admitted he made a horrible call and apologized to Galarraga immediately after the game.
The technology is there to use instant replay to improve the quality of games for fans, players, and coaches alike, even if it comes at the marginal detriment of umpires. Let's do what football has done and expand the use of technology and get the calls right. Expand the use of instant replay.