Not sure what the booth was talking about but it was probably nowhere close to being right.
Taken directly from mlb.com
Outs Above Average starts with Catch Probability, which takes the distance an outfielder must go, the time he has to get there, and the direction he travels to put a percentage of catch likelihood on each individual batted ball. Outs Above Average is the season-long cumulative expression of each individual Catch Probability play. For example, if an outfielder has a ball hit to him with a 75 percent Catch Probability -- that is, one an average outfielder would make three-quarters of the time -- and he catches it, he'll receive a +.25 credit. If he misses it, he'll receive -.75, reflecting the likelihood of that ball being caught by other outfielders.