Ubaldo Jimenez: Head-Scratcher of the Year

Last year’s amazing first half and full season performance supported by luck metrics that were unsustainable caused Ubaldo Jimenez to be overvalued in 2011 drafts. Of course, although many expected some regression, likely no one could have predicted an ERA of nearly 4.50 and a mid-season trade into the American League. For some context, let’s compare his 2011 skills with another skill set:

These three skill sets look pretty near identical, right? Above average K% and GB% marks, and below average BB%. In fact, you might even say that this appears to be the same pitcher. You would be right. Pitcher A is Ubaldo in 2011, Pitcher B in 2010 and Pitcher C in 2009. Those skills have led to SIERAs of within just 0.19 runs of each other and xFIP marks in a narrow range between 3.59 and 3.66. So, this seems like the same pitcher pitching the same way as he always has.

Yet, his ERA has gone from 3.47 to 2.88 to this year’s disappointing 4.49. This is a great example of why I continue to mostly ignore ERA and focus on process when projecting future performance. Jimenez’s BABIP, HR/FB and LOB% have jumped around and been the primary cause of his ERA fluctuation. Did he go from one of the best in baseball in suppressing home runs to suddenly becoming league average? Did his skills stranding runners or avoiding hits on balls in play disappear overnight? Of course not. This is just like as a baseball player where small sample sizes over just one season rule.

Now, this was not solely an article about Jimenez having been unlucky this year, likely leading to undervaluation next year. Aside from that, the biggest mystery is his loss of velocity. Over the last three years, he possessed the highest average fastball velocity among qualified starters, reaching 96.1 miles per hour in the previous two seasons. This year, however, his fastball has dipped to just 93.4 miles per hour and has remained relatively stable all season long. Looking at his PitchF/X velocity charts, it appears that only once has his velocity in a game average 95.0+ miles per hour. Last season, it was rare for his fastball to average below that velocity.

Despite a K/9 identical to last year and a K% higher than 2009, but not too far below last season, his SwStk% has taken a dive. Given the apparent quality of his stuff, his SwStk% has actually never been as high as one would expect. But this year, it is below league average for the first time in his career. I am guessing that his decreased velocity is the main culprit and thinking all this ties into his career worst BABIP and worst HR/FB ratio since 2007. In addition, his F-Strike% is at a career worst, even though his BB% dropped from last season and is just a hint worse than his career best mark in 2009.

So, according to the underlying metrics we typically analyze, Jimenez has pitched at the same level as he always has, but the luck dragons have taken a bit out of his season. But given his huge unexplained velocity dip and some other weird numbers in his advanced metrics, he has been quite the enigma this season. If his velocity does not improve next spring training, he may not be as undervalued as we might expect and a full rebound is less of a guarantee.