Sean West's peculiar season

Sean West had quite the strange season last year.  The last of five pitchers taken by the Fish in the 2005 Draft, coming up through the minors he was a strong GB pitcher with a lot of strikeouts, but with questions about his control.  For example, last year in Jupiter he had a strong K rate (21.6%, 8.2 per 9), low FB% (30.9%), and a lot of walks (14.1%, 5.4 per 9).

But his positives went right out the window in 2009.

2009 was the first time Sean West would reach the high minors, pitching for the Double A affiliate Jacksonville Suns.  And in his first eight starts, things weren’t pretty.  He still struck out a lot of batters (25.8%), but his control was still a problem (11.3%).  Most importantly though was his home runs and fly balls.  His FB% jumped to 40.2%, and he had a massive HR/9 of 1.90!  This led to an ERA of 4.85 and FIP of 5.14.

But the Marlins were unaltered and, desperately needing an arm in the rotation, called up Sean West to the big league club.  He still had a walk problem (11.4%), but his strike out ability complete disappeared (11.8%) and he only finished with one strikeout more than his walk total.  He was still giving up way too many fly balls (45.7%), and even a low HR/FB% couldn’t keep his HR rates from being bad (1.15 per 9).

After 10 starts with an ERA of 4.91 and a FIP of 5.33, the Marlins sent him back to AA for four games (3 starts).  Back down, his strike out rate lowered from where it was before (16.3%) and he still allowed a ton of fly balls (43.7%) and home runs (1.27 HR/9).  His control showed a lot of improvement though, lowering to 6.5%.

Again in need of a starter, the Marlins called him back up to major league level to finish out the season.  And Old Sean West was back.  He raised his strike out rate to an above average 18.6%, as was his control at 7.2%.  Most importantly, the ground balls were back.  He’d allow a FB 35.3% of the time, not quite his 2008 number but a 10% improvement over his previous call up.  His xFIP during his second call up would be a very nice 4.11.

And to make things more easily to compare, here’s a table:

League IP K% BB% FB% HR/9 FIP
A+ (2008) 100.7 21.6% 14.1% 30.9% 0.27 3.55
AA (2009) 64 22.6% 9.8% 43.7% 1.69 4.92
MLB (1st) 55 11.8% 11.4% 45.7% 1.15 5.14
MLB (2nd) 48.3 18.6% 7.2% 35.3% 0.75 3.57
MLB (total) 103.3 15.0% 9.4% 40.8% 0.96 4.49

Can PitchFX tell us anything about the split between his first call up and second?

The first thing to look at would be his pitch usage.  In his first call up, he went to his fastball 70.3% of the time, his changeup 8.9% of the time, and his slider 20.8% of the time.  His second call up, he went to his changeup a lot more.  He threw it 19.5% of the time, lowering his fastball usage to 61.3%, while his slider usage stayed static at 19.1%.

So then, did his changeup generate more ground balls?  Let’s take a look:

Pitch GB% FB% LD%
Change Up 52.6% 28.1% 19.3%
Fastball 36.0% 40.7% 23.3%
Slider 40.3% 40% 16.7%

So it would in fact seem that his change up is the reason for more ground balls.  Although I do feel it’s worth noting all of his pitches saw increased GB rates in his second call up.

So what can we expect out of Sean West in 2010?  It’s hard to say.  What we do now is that he’ll probably still have control problems, and he’ll probably still strike guys out.  But his FB and GB rates have to continue to stay at the rate they were in his second call up if he wants to continue to be a good MLB pitcher.  And as of this moment, it’s hard to say that they will with any certainty.

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