What Went Wrong With Jonathan Sanchez

On Tuesday afternoon, the Kansas City Royals designated left-handed starter Jonathan Sanchez for assignment. The Royals, of course, acquired Sanchez and rightleft-handed pitcher Ryan Verdugo from the San Francisco Giants over the winter, in exchange for Melky Cabrera. At the time, the trade came in for criticism and praise on both sides, which suggested it was a fair deal. Obviously, it was not.

Sanchez started 12 games for the Royals this season but pitched only 53 1/3 innings, an average of fewer than six five innings per start. He was on the disabled list from early May to early June with left bicep tendinitis, the same maladay that kept him the disabled list for more than a month last season. With the Royals, Sanchez’s strikeout rate (6.08/9), walk rate (7.43/9), batting average against (.294), and WHIP (2.04) were all the worst of his career. His FIP was 6.42, the highest in the majors for starters with more than 50 innings pitched.

Throughout his career, which began with the Giants in 2006, Sanchez battled problems with his command. His walk rate never dipped below 4.00/9, even in 2010, his best season in the majors. And yet, there were games — and stretches of games — when Sanchez was quite effective. His no-hitter against the San Diego Padres on July 10, 2009 is one example, but there were others. Because even when Sanchez was wild, he still possessed — until this season — “swing-and-miss” stuff.

Let’s look at some video first, and then delve into the numbers.

Here’s a clip from a Sanchez start in September, 2010 against the Dodgers in Los Angeles, as the Giants were battling for the National West title. Sanchez struck out nine: one looking, five swing-throughs on fastballs and three swing-throughs on off-speed pitches.

Sanchez had a similar game against the Arizona Diamondbacks in May, 2011. Seven strikeouts, one looking, and six swing-throughs: three on fastballs, three on off-speed pitches.

But there are no MLB clips of six and seven strikeout games for Sanchez this season. His season high was five strikeouts in an April 24 game against the Cleveland Indians. He also walked seven in that game.

What happened?

Here are some numbers. They’re not all the numbers you can look at, but the ones I found most interesting, for the 2010, 2011, and 2012 seasons.

Notice the drop in Sanchez’s fastball velocity, coupled with the increase in his change-up velocity. In 2010, the difference in speed between his fastball and his change-up was 8.7 mph. This season the difference shrunk to 5.9 mph. At a slower speed, his fastball was easier to hit, and at a higher speed, his change-up was easier to detect, resulting in fewer swing-throughs on both pitches. That’s corroborated by the drop in Sanchez’s O-swing numbers over the last three seasons.

What accounts for the changes in Sanchez’s velocity since 2010? Perhaps it’s the left bicep tendinitis that’s bothered him since last season. Or changes in his mechanics. Or maybe it’s the fact that Sanchez will turn 30 years old in November. The last factor would be consistent with the analysis of my colleague Bill Petti, who has studied the decline in velocity as pitchers age and how it affects performance.

Whatever the cause, Sanchez’s declining fastball velocity and increased off-speed velocity tipped the balance, changing him from an effectively-wild pitcher to a wildly ineffective one.