Kansas City Royals: Examining the Decline of Joakim Soria

Ned Yost and the Kansas City Royals announced after a second blown save in as many days that Joakim Soria, one of the best relievers over the last four seasons, had lost his job as closer to Aaron Crow. Soria, who has only converted seven saves in 12 opportunities, saw his ERA balloon to 6.55 and his WHIP increased to 1.68 for the season after Monday's performance.

So what has led to Soria's downfall in 2011? First off, Soria's ERA is somewhat inflated by a .338 BABIP and a 64.8 percent strand rate, but his xFIP of 4.06 is still above his career 3.23 mark. Soria's stuff has seen a major drop off this season. Soria's average cutter velocity dropped from 91.7 mph to 89.4 mph , while his average fastball velocity dipped from 93.4 mph to 90.9 mph. 

With the drop in velocity, Soria's 7.1 swinging strike percentage is the lowest of his career (percentage of 10.8 for career), and hitters are chasing fewer pitches out of the strike zone.

The percentage of pitches out of the strike zone that opposing hitters have swung at has dropped from 30.8 percent in 2010 to 18.5 percent this season. This drop explains the decline in Soria's peripherals. His walk rate has increased from 2.19 to 4.09 BB/9, and his strikeout rate has declined from 9.73 to 7.77 K/9.

Additionally, hitters are hitting the ball harder off of Soria this season. His line drive percentage has increased from 17 percent to 23.2 percent, while his fly ball percentage has increased by 3 percent and his ground ball percentage has dropped by 10 percent.

The Royals and Soria have insisted that he has not sustained any injury, and the signs seem to point that this change is a temporary one.

However, the stats show that Soria's problems are not mental, and that his stuff has clearly deteriorated. I'm sure Soria could be an effective reliever despite his decreased velocity, but I find it hard to believe he will return to his dominant form without it.