I really want to believe Zito is back.  I want him to be a good pitcher for the Giants, as I’m sure pretty much all of you do.  But I don’t trust him yet.  He’s used up all of his trust points.  So, what do I do when I’m confused and vulnerable?  I check out the stats to see if I can confirm some of my biases.  I’m just going to throw some numbers out, from FanGraphs and StatCorner, and see if we can find anything.

Glossary:

FBv – Fastball Velocity

SwStr% - Percentage of strikes that are swinging.  These have a direct linear relationship with K%, so this can be an indicator if a pitcher has been strikeout lucky or unlucky.

uBB% - Percentage of batters walked unintentionally.

Ball% - Percentage of pitches thrown that are called balls.  From StatCorner: The R2 of Ball% to walks is roughly +.56 on a cubic formula.

HR/BIA – Homerun per Ball in Air (line drives + flyballs + pop ups)

Ok, so that’s some data that might not be easy to wade through if you’re unfamiliar with it.  In case you couldn’t tell, I bolded the years with the Giants and I also bolded some numbers in the tables that are pretty severe outliers for this year.

Let’s start with his fastball velocity, which has been brought up many times as the reason for his success so far.  I’m not sure that that conclusion can be drawn, given the data above.  Although 3 of his 4 best seasons by FIP were in his 3 highest velocity seasons, his 3rd best season was in his lowest velocity year, 2007.  I don’t know either way, but I’d be hesitant to just credit the improved velocity, especially considering a few of the other numbers we’ll get to.

Next up, strikeouts.  Obviously, they are up around the highest they’ve been since 2002 and that is good.  Is he getting lucky?  Well, based on his SwStr%, I don’t think he is getting too lucky.  His SwStr% is league average and his K% is a bit above average, so it seems reasonable with maybe a little regression coming.

Now we get to something interesting, Zito’s BB%.  So far, this is the best BB% he’s put up, BY FAR, since his 2002 Cy Young season.  I have serious trouble believing this is real.  This number stabilizes fairly quickly, so you can’t easily just waive it off as small sample size, but I’m still skeptical.  The good news is, he is throwing fewer balls in general, so, if he can somehow keep this up, he should be able to put together a good season even with some regression in his K%.

His BABIP is mostly uninteresting, given that it’s a completely reasonable number, but when looked at in conjunction with GB%, it’s a little odd.  Speaking of which, Zito is getting WAY more groundballs than he ever has.  As with his walk rate, this makes me raise an eyebrow (just one).  I’m not sure of the precedence for pitchers dramatically improving their groundball rates.  I’m sure it’s happened before but I don’t know how common it is.  My guess would be that it’s pretty rare and would usually result from the development of a new pitch.  Someone who’s good with Pitch f/x might be able to point to something, such as better movement on his pitches, but for now I’m just going to shrug my shoulders and point to the BB% paragraph above.  Anyways, back to my first sentence about BABIP.  Typically ground balls become hits more often than flyballs, so it’s interesting that Zito’s GB% is so low considering he’s getting so many groundballs.  This most likely can be explained by small sample size, so if Zito keeps up the groundballing ways you can expect a few more hits to fall in than have so far.

Lastly, we come to something that will surely regress, his HR/BIA.  The lowest rate in 2008 among starters, was Cliff Lee at 3.32 (Timmy in 2nd at 3.53) and Zito’s current number is horribly out of line with his career.  In fact, 2007 was pretty out of line for him since 2003, so either he’s figured out the secret of how to not give up homers, or he’s been pretty lucky for the last 1+ season.  Expect some regression here.

Soooo, what does this tell us?  Well, I’m not entirely sure.  Yes, I just wasted a lot of your time, sorry.  It’s pretty clear he’s going to be giving up a few more homeruns, but other than that, I’m left scratching my head.  I really don’t trust his current BB and GB rates, but I don’t just want to write them off either.  Clearly, we need to see more to be sure.  Please chime in with your thoughts, stat based, eye based, hunch based, or divine-message-in-your-sleep based.  Also, please feel free to correct me if I’ve messed up analyzing the numbers anywhere.