In 2012, Mike Trout burst onto the Major League scene with what can be considered one of the greatest rookie campaigns of all time. While he was a strong offensive player and baserunner, Trout made defense his calling card. As he ran, jumped, and dove across the field making one great play after another, the industry became enamored with his defensive ability. However, that defensive success did not carry over into his sophomore season as his defensive ratings were down across the board.

Many individuals may claim that this is due to a flaw in the manner by which defensive metrics are calculated, but the data shows that this may very well be a case of confirmation bias. Rather than trust the data that helps lead to conclusions, individuals use their own preconceived notions to justify Trout’s defensive prominence. Digging into the numbers shows a few noticeable aspects of Trout’s game that have changed.

A good place to start is with the part of Trout’s game that got everyone’s attention: the Good Fielding Plays (GFPs). In 2013, Trout tallied 24 total GFPs (similar GFP types have been grouped here):

These plays are fine and dandy, but there is a noticeable difference between his 2013 GFPs and his 2012 GFPs. The general theme is that there are fewer of them:

When good fielding plays occur, it is tracked whether the play saved the team a base or created an unexpected out. By looking at Trout’s 2012 GFPs, he recorded 28 unexpected outs and saved 3 additional bases (twice saving second base and once saving third base). In 2013, Trout has only recorded 23 unexpected outs and has only saved 2 additional bases (second base in both cases). However, the difference between 2012 and 2013 is bigger than this difference, as three of the additional unexpected outs recorded in 2012 were robbed home runs. This means the prevention of guaranteed runs being recorded instead of prevention of hits.

While Trout made fewer GFPs in 2013 than he did in 2012, he made the same number of Defensive Misplays and Errors:

Trout had fewer miscellaneous DMEs such as slipping or hesitating in 2013, but he racked up misplays in categories that are a more routine part of his duties as an outfielder. As may be noticed right away, Trout had three more balls bounce off his glove this year than last year, which essentially makes up the difference between flyball GFPs (assuming that the “Ball Bounces Off of Glove” DMEs would be GFPs if the plays were made). Trout also had a couple of routes so bad that they have cost him outs, and he had a much tougher time playing balls at the wall. Instead of robbing home runs at the wall and making great plays, he misplayed five balls at or off of the wall that have cost him outs and bases.

The DMEs here suggest is that Trout’s ability to judge plays may have decreased from 2012 to 2013. While he had three fewer failed dives at balls, he also misplayed five balls at the wall, made two mistakes in breaks and routes, and threw to the wrong base on two occasions. There could be many explanations for this, but Trout is likely the only one who can truly explain any differences since judgement is a mental process.

On whether or not Trout has actually become a worse defender, the jury is still out. There are certain aspects that Trout doesn’t have control over such as whether balls are hit in a spot that he can rob a home run. Along with that, Trout had a few instances where a ball bounced off of his glove rather than being caught for a likely GFP, and if these instances are a matter of inches, there may not be any loss of skill at all. However, there is also an apparent negative trend in the ability to make judgement plays. In all likelihood, Trout’s abilities as a defender lie between what he did in 2012 and in 2013. He still has the physical abilities, so it’s just a matter of overcoming the lapses in judgement.