When Trout arrived at the Angels’ spring training facility in 2018, he had a very specific request: to see the numbers. He wanted the front office to present him with the advanced analytics that painted him as a subpar defensive center fielder so he could pinpoint the areas to improve. Specifically, he wanted to compare his metrics to those of Jackie Bradley Jr., Kevin Kiermaier and Byron Buxton.
Among the 17 center fielders with enough innings to qualify in 2017, Trout ranked 13th in ultimate zone rating (minus-4.4), 12th in defensive runs saved (minus-6) and 13th in FanGraphs defense (minus-2.8). He spent the ensuing spring reading balls off the bat during batting practice on a daily basis and continued to work tirelessly on both his arm strength and his accuracy.
That led to significant improvements in all three of the aforementioned numbers — 4.0 ultimate zone rating, 8 defensive runs saved, 5.8 FanGraphs defense — and nearly won Trout his first Gold Glove.
Source: Alden Gonzalez, ESPN.com