Being an umpire, I’m always interested while watching a Major League game, when an appeal is made regarding a call. Umpires are human and humans are prone to error—but umpires may be less prone to error than many people assume.
If you’ve been living under a rock, MLB now allows certain plays to be reviewed upon request by one of the two teams. This change occurred when the powers that be initiated expanded instant replay during the 2014 season, thinking that it would improve the game. And interestingly, over the first season of reviewing a plethora of calls, the umpires made the right call almost all of the time. For all the ins and outs of instant replay and what calls can be reviewed, the Wikipedia entry on instant replay is really good and gives a great overview.
Fans and players have always had an adversarial relationship with officials. Both of them are far from being objective about whether the right call is being made. They have inherent bias built into their reaction to close calls, especially if that call goes against their teams, or them personally.
(Photo by James Brosher/AMERICAN-STATESMAN – Home base umpire Mike Lusky signals safe as Express first baseman Brian Bogusevic slides into home plate.