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July 10, 2012

Fantasy Beat

Shields' Plummeting Groundball Rate

by Jason Collette

James Shields picked up in 2012 where he left off in 2011, winning five of his first six decisions while posting an ERA of 3.05.  The first month of the season even saw Shields do something better than he had ever done in the past: generate groundballs.

As good friend Tommy Rancel noted in mid-May, Shields had the third-highest groundball rate in the American League at one point, behind only Derek Lowe and Jason Hammel. In that same piece, Rancel noted that Shields was generating a high amount of groundballs in an unconventional manner. Most pitchers use sinking fastballs to generate groundballs, but Shields was getting it done using his secondary pitches. 

Shields’ rising groundball rate came at a time when the Rays’ infield was fully healthy, as the team didn’t lose Evan Longoria to injury until the final day of the month.  From that time forward, however, the defense has suffered. In fact, Joe Maddon has used seven different players at third base in Longoria’s absence: Sean Rodriguez, Jeff Keppinger, Will Rhymes, Drew Sutton, Brooks Conrad, Elliot Johnson, and even Chris Gimenez. That septet has committed 15 errors while wearing the hat of replacement level player.  Later, Matt Joyce would become injured, forcing noted defender Ben Zobrist to spend more time in the outfield rather than at second base, forcing less rangy players to field Shields’ grounders.

The effect of the replacement level defense may be playing out in how Shields is attacking hitters; his high groundball rate is now a thing of the past. Through his first 12 starts this season, Shields generated a 58 percent groundball rate. Since then, that rate has absolutely plummeted to 27 percent.

During that run, Shields has clearly changed the pitch mix from earlier this season, but the new mixture has brought less success:

James Shields 2012 Pitch Mix