Both the arguments provided by the proposition are faulty.  First, the vast majority of umpires’ calls might be correct, but that’s because the vast majority of calls are completely uncontroversial. The question is what percentage of difficult calls do umpires get right. And it would appear that umpires do not stack up well. An ESPN study of close calls found that umpires get over 20 percent of them wrong. [1] More frequent use of instant replays might correct some of these calls, but it would do so at the expense of severely damaging umpires’ credibility, which would impair their ability to do all the other important aspects of their job.  Second, in crucial moments, it’s imperative for umpires to be especially attentive, and for them to make conclusive decisions. If umpires know that they don’t have to get the call right because the cameras can save them, then they’re more likely to get it wrong. And if umpires’ decisions are not final, then what should be the most exciting moments in baseball games will be supplanted by monotonous waiting for umpires to review the footage.  [1] T.J. Quinn and Willie Weinbaum, “Study shows 1 in 5 close calls wrong,” ESPN.com, Aug. 16, 2010,