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Tuesday, April 15, 2014

Homer Bailey's Bizarre Season

Homer Bailey: Down but not out.
Photo Credit: Keith Allison
Homer Bailey is having a rather absurd start to the season.  Check out his line, hot off the presses from FanGraphs:
The top row is his performance from last night's game alone.  It wasn't pretty.  He gave up 5 runs on 8 hits in 5 innings, including four home runs***.  The last two were particularly horrible to watch: the Reds had just come back on a Ryan Ludwick two-run homer to take the lead, and he immediately gave up back-to-back home runs to Starling Marte and Travis Snider.

The bottom row, in gray, are his 2014 totals.  Currently, Bailey has an awful 8.16 ERA.  And a miserable 7.25 FIP.  But he also has a 2.78 xFIP.  Which one of these is not like the other?

Why?  Look at the elements of his line that are the most volatile: BABIP, HR/FB %, and LOB%.  All of these numbers tend to show very little consistent pitcher "skill."  They often vary unpredictably from year to year across a pitcher's career, and as a result we tend to attribute most of the difference from league average for these statistics to "luck."  We're in the extreme small sample size segment of the season, so deviations from league average on these stats should be treated as completely unsustainable.  So, with that in mind...Bailey's Left On Base percentage is pretty typical, but his Batting Average on Balls in Play is an absurd 0.429 (league average is usually around 0.300, Bailey's career BABIP is 0.300).  And his Home Run per Fly Ball rate is even more absurd at 60% (league average is usually ~12%, Bailey's career rate is 11%) .  These are the numbers that experience has taught us to ignore.

Now let's focus on the numbers that are the most stable: K/9, BB/9, and GB%.  These numbers all look really good.  His walk rate is a bit higher than usual (career 2.9 BB/9), but his strikeout rate thus far has been outstanding.  And his ground ball percentage is actually up compared to the rest of his career at a very good 51% (career 44%, 46% last year).  Furthermore, while it's not shown above, his velocity has been just fine (only 1st two starts shown, but yesterday he was sitting 94 mph with his fastballs once again, and topped out at 96.5 mph):

I don't know if I buy that the large swings in BABIP, HR/FB%, and LOB% are really "luck," as in something completely out of control of the pitcher.  If Bailey is missing with his pitches and leaving hanging curveballs (to Marte) or grooving fastballs (to Walker, Sanchez, and Snider), they're going to hit the ball out of the park.  But past work has shown that these trends tend to not be predictive of future performances.  Pitchers either make adjustments to correct those problems...or their luck changes.

In contrast, the numbers that are predictive are quite positive for Bailey's future starts.  He's getting lots of strikeouts, he's getting a good number of ground balls, he's basically walking guys at his normal rate, and his velocity is just fine.  We're in small sample size even for those numbers, but I just don't see anything that would cause me to be particularly concerned about Bailey's next several starts, or his season.

So, let's all take a deep breath...and hope for better things in the future.

*** One thing more bizarre that Bailey's start to the season is last night game.  10 home runs in 6 innings, all in the midst of a downpour that finally(!) led to a rain delay.  I've nothing to say about that game that hasn't been said, but yeesh.

Source: FanGraphs