Wednesday, May 31, 2006

The Importance of Defense (And Why The Tigers Are Winning)

The argument can be made that Detroit Tigers starter Nate Robertson is coming into his own this season. After two straight seasons of relative mediocrity, Robertson has stampeded out of the gates this year, catapulting him to the forefront of the team’s rotation. And all the while, he looks like the same guy on paper – hell, possibly worse even – than the past two years.

Most sabermatricians will attribute this to luck and defense. The most consistent measure of a pitcher is his peripherals (strikeouts per nine, walks per nine, homers per nine, strikeouts to walks, etc.), and when a pitcher outperforms those peripherals, the word “luck” begins circulating. And, by all appearances, Robertson is getting rather lucky this year. But how can we predict if this luck will hold up?

[MORE]Other than luck, the other assisting factor for a pitcher is the defense behind him. Defensive statistics at this point aren’t the most efficient measures, but there are certain statistics that can help us determine which teams play the best D. The best of this crop, in my opinion is Defensive Efficiency, as compiled by Baseball Prospectus. Simply defined, it is the rate at which a team converts balls in play into outs. And, surprise surprise, Detroit is ranked No. 2 in the Majors, first in the American League. And wouldn’t you believe it, the White Sox are second in the AL, followed in order by Toronto, the Yankees, and Boston. The bottom teams: Minnesota, Tampa Bay, Cleveland, and Baltimore. One glance at the standings, and you’ll get the point.

Let’s step back to last year for a second. Detroit ranked eighth in the AL in Defensive Efficiency, converting 2.4 percent fewer batted balls into outs. And just to put that 2.4 percent into perspective, the difference between the top team in the AL – Detroit at 72.8 percent – and the bottom team – Minnesota at 64.7 percent – is 8.1 percent (as if you couldn’t do the math yourself). For a large sample size study, the difference between last year’s top defensive team, Oakland, and the bottom team, Kansas City, was 4.8 percent. So yes, that 2.4 percent rise is a rather significant one. And, just because it will have relevance later in this analysis, Detroit converted 69.6 percent of batted balls into outs in 2004, right around their 2005 mark.

As a digression, a defensive improvement has vastly benefited the Yankees this season as well. Sitting at 10th in the AL last year, the Yankees converted 69.8 percent of batted balls into outs. And just to make another digressing point, Boston was right behind them with 69.2 percent. This year, the Yanks are at a 71.4 percent conversion rate, a more than modest improvement. And it’s shown, as the pitching staff has performed much better to date. And Boston, for all their perceived defensive upgrades, is at 70.9 percent this year. Basically the same improvement rate, but they’re still worse than the Yanks. That is kind of sad, considering all the defensive moves Boston made this winter, countered only by the addition of Johnny Damon by the Yanks. Digression over.

Let’s take a look at Robertson’s peripherals from the past three years, followed by his output (i.e. ERA):


Quite simply, he’s doing everything worse this year, except he’s keeping the ball in the park at a better rate and he’s kept his ground ball to flyball ratio on par. But to offset that, he’s walk rate has increased to a greater degree than his strikeout rate, and he’s throwing more pitches per batter faced. All of these factors would point to a downward movement. So it appears that Robertson is the beneficiary of a combination of luck and defense.

For a luck and defense factor, we can turn to Batting Average on Balls in Play, a statistic – as shown by the studies of Voros McCracken – that is largely based on luck and defense. The idea is that pitchers have little to no control over what happens to a ball once it is put in play. In 2005, Robertson was the bearer of a .285 BABIP, which is right around the normal number (defined by Baseball Prospectus as .290). This year, he’s lowered it by a full percent, sitting at .275. Rise in defensive efficiency, drop in opponent’s BABIP. It all seems to make sense.

Here’s where things become a bit more perplexing. As my fascination with the plethora of statistics over at Baseball Prospectus grows, I’ve been homing in on the quality of batters faced by a pitcher. This takes the BA, OBP, and SLG of the batters faced by a particular pitcher to determine the quality of the hitters they face. This helps weed out early spurts of greatness, as many pitchers face an easy schedule early, and falter once they start to face better hitters. One would think that given Robertson’s situation, he would be facing lower caliber hitters. That would explain the status quo peripherals and the improved outcome. But…

Robertson’s 2005 Quality of Batters Faced: .264/.328/.417
Robertson’s 2006 Quality of Batters Faced: .267/.338/.428

So while he’s keeping his peripherals on par with years past, he’s facing tougher hitters and allowing them fewer hits on balls put in play. This is quite remarkable for a guy who doesn’t boast a high strikeout rate and sits on rather average strikeouts to walks and groundball to flyball ratios.

As noted, the defense certainly plays a part in this. Teammate Mike Maroth is another example of the defensive benefit, as he’s maintained his peripherals from last year (actually, his K/BB and GB/FB ratios have plummeted) and is seeing much more success in this campaign. And, as with Robertson, he has been facing hitters of a higher caliber (.260/.323/.409 last year vs. .267/.334/.422 this year).

Furthering the idea that the Tigers defense has been the key this year is Jeremy Bonderman. Unlike Robertson and Maroth, Bonderman is a strikeout pitcher. And, as could be expected from a 23-year-old, he has seen a spike in his peripherals this year, most notably in strikeouts per nine (6.91 to 7.42), strikeouts to walks (2.54 to 3.05), and GB/FB (1.52 to 1.72). Yet, Bonderman’s ERA has stayed relatively the same (4.57 to 4.61).

The easy answer is that the increase in quality of batters faced has more adversely affected Bonderman than his teammates. But, uh, there’s a problem with that; he’s faced relatively equal talent from last year to this year.

2005: .267/.335/.428
2006: .266/.336/.423

This may be slightly attributable to luck, seeing as Bonderman’s BABIP has gone up .013 points this year, which has amounted to roughly four more hits to this point.

Obviously, a more in-depth study is warranted for these Detroit Tigers. The wisdom we’re seeing across the Internet these days is that strikeout pitchers are highly preferable to finesse pitchers, yet the Tigers finesse crew has seen a vast improvement this year while their strikeout guy has been relatively on par as far as output goes. The guys who rely on defense are winning, mainly because the team defense has improved, and the guy who relies on his own arm is ho-hum. And while we don’t have data from last year to put things in a better perspective, rookie Justin Verlander is looking to be of the finesse type, and he’s having wild success this year. Same goes for good old Kenny Rogers.

If the Tigers defense continues to reel in balls in play and they can swing a deal for another finesse pitcher before the trade deadline, they could rise from “yeah, they could maybe pull this off” to “now we’re in control baby!” status. This notion is furthered when you take a look at the Quality of Batters faced for the defending champion White Sox.

John Garland: .258/.320/.412
Jose Contreras: .261/.324/.409
Javy Vazquez: .266/.331/.420

That’s good for the lowest, second lowest, and fourth lowest in the AL for OBP, and third, first, and 18th in SLG (both respectively). It should also be noted that Mark Buehrle is the sixth lowest in SLG faced, while Freddy Garcia is 16th. Once they get into the meat of their schedule, the White Sox could be headed back to Earth.

The cliché is “Defense Wins Championships,” and the Detroit Tigers are out to prove it.