In Shields' defense, Padres aren't Royals

James Shields reportedly has agreed to a four-year deal worth more than $70 million with the San Diego Padres. Shields’ durability has been a strong point, as he has eight consecutive seasons of at least 200 innings pitched. As Shields moves from the Kansas City Royals to San Diego, several changes could affect his performance. Though he no longer will have to regularly face designated hitters, Shields is moving from a team with the best outfield defense to one that projects to be near the bottom of the National League.

In the past two seasons, Shields has benefited greatly from the Royals’ outfield defense. In that span, Shields has allowed a 34.4 percent fly ball rate, which is above the major-league average for qualifying pitchers in that span. On fly balls traveling at least 250 feet, Shields allowed a .186 batting average, fourth-lowest among pitchers to have at least 250 at-bats end with a fly ball traveling at least that far.

A large component of the low batting average against Shields on these fly balls was the quality of the defense behind him. In the past two seasons, the Royals had three players in the top 10 in MLB in defensive WAR.

Royals OF defensive ranks, 2013-14

In San Diego, the outfield behind Shields will be known more for the quality of its offense than of its defense. In the past two seasons, none of the three primary Padres outfielders rank in the top 200 outfielders in defensive WAR.

Padres OF defensive ranks, 2013-14

What these numbers do not consider is that one of these players has to play center field. Of the three outfielders expected to start, only Matt Kemp has significant playing time in center field. In 827 games in center field, Kemp has minus-72 defensive runs saved. Myers also has experience at the position, but he has not played there regularly since he was at Triple-A Omaha in 2012.

Should things be bad enough defensively for the Padres, they could turn to Cameron Maybin as their centerfielder. Maybin has had positive defensive numbers in center field in three of the past four seasons.