What’s Behind the Rotation’s Improvement?

Make no mistake: the start of the Indians’ season has been fun. For those keeping track at home, they’re off to the second best start in franchise history, due to a strong offensive showing, improved defense and strong starting pitching.

And while I think plenty of people expected the Indians to have a reasonably strong offense this season, just a few weeks ago most people were fairly skeptical of the rotation, and for good reason.  Our “ace” hadn’t had a truly effective season in four years.  Our #2 starter was only 23 years old and had already developed quite a proclivity for allowing home runs.  Many argued that our #3 pitcher should be in the bullpen.  The rest were labeled as cast-offs or back-end fodder, just filling spots until the draft picks arrive.

So quite naturally, the Indians’ rotation has been dominant so far.  Through Monday night’s game, the rotation has posted the third best ERA in the American League.  And remember, that includes the first two starts of the season, which were, admittedly, horrendous.

For a rotation that was predicted to be so bad, how did this happen?  And more importantly, can it continue?

There’s no real answer to these questions, of course.  If we could know what is going to happen, that would take all the fun out of it anyway.  But when I want to try to separate good luck (that’s not likely to continue) from improved skill (that is) I usually look at two quick statistics: (1) the pitcher’s batting average on balls in play and (2) his strikeout-to-walk ratio.

Batting average on balls in play (BABiP) measures how often a batted ball becomes a hit.  Believe it or not, pitchers have less control over this than you might imagine: with enough plate appearances, nearly every starting pitcher’s BABiP usually normalizes to around .290-310.  So if a pitcher’s BABiP falls too far outside of that range, we might assume that luck is playing a role, and we’d expect things to even out as the season continues.  If you’re interested, read this primer I wrote last season.

Let’s look briefly at our rotation’s performance so far this season as well as career rates*:

*You’ll notice that Tomlin and Carrasco are furthest from the .300 or so league average BABiP for their career.  They also have faced the fewest batters.  I’d expect their career rates to normalize by the end of this season, if they log anything resembling significant innings.

Every pitcher in our rotation has a BABiP in 2011 well below his career average.  You might be tempted to say that the drop is a result of improved defense, and I’d probably agree, to an extent.  On the other hand, no starter in baseball history—even those with the best defenses ever—has ever been able to sustain a rate as low as Justin Masterson, Josh Tomlin, and Fausto Carmona boast in 2011.  I’d expect those figures to rise a bit as the season continues, and with it, their ERAs.

But that’s not to say all is lost.  A metric that points more to repeatable skill rather than luck is a pitcher’s strikeout-to-walk ratio (K/BB).  A decent pitcher strikes out two batters for each walk he allows.  A good one strikes out three.  A quick look at the leaderboard in 2010 should illustrate that good pitchers always have good K/BB rates; you’ll recognize the first guy on this list:

It’s no coincidence the top five in K/BB rate last season were also five of the best pitchers in baseball.

So here is how the Tribe’s rotation has stacked up in so far in 2011 and for their respective careers:

And from this table we see some real improvement—improvements that might be more sustainable than a drop in BABiP.  Every pitcher but Tomlin has improved his strikeout-to-walk ratio considerably, and this demonstrates—to me at least—that there could be some real and durable gains being made by our pitching staff.

For example, Carmona has always struggled with allowing walks—9.3% of batters faced for his career have been issued a free pass.  But so far this season he’s cut that rate to only 6.9%.  Justin Masterson’s rate has also dropped from 9.1% in 2010 to 5.0% in 2011.  Those are real improvements that I’d be hesitant to dismiss as luck: they are pitching better.

We don’t know enough right now to say exactly how the rotation will fare for the rest of the season; that’s something only time will reveal.  But we do have some reason to believe that our rotation is currently benefitting both from some good luck and some improved skill.  I don’t believe the starting five will be as good as they have been for the rest of the season.  But by the same token, I’m starting to think that they might be a lot better than I thought they’d be coming into the season.

I guess that’s one of the advantages to having such an inexperienced staff: young dogs can learn new tricks.