28 Days Later: Why Derek Jeter's 2010 Stats <i>Still</i> Don't Make Sense

About a month ago, I wrote an unintentionally controversial article about some puzzling patterns in Derek Jeter’s early season numbers.

There were two main contradictions within his statistics: that he was on pace for the best power numbers of his career while posting his highest ground ball rate ever, and that he was posting a career-low strikeout rate while swinging at a dramatically larger proportion of pitches thrown outside of the strike zone.

My critics claimed that I was reading too much into the stats too early in the season. Under normal circumstances I would have agreed, but it was more than the numbers themselves that were puzzling. When a person hits more home runs on fewer fly balls and makes better contact with worse pitch selectiveness, the results contradict the logic, no matter how small the sample size.

Four weeks later, I think it’s appropriate to revisit the situation and see how things are shaping up.

Overall, the discrepancies have become less dramatic, but the contradictory trends are still in place.

As I predicted, his power numbers have come back down to earth. He’s now on pace for 16 homers (down from 26 at last writing) and 98 RBI (down from 130). Neither would be a career high, but both would be above his norm.

But Jeter’s unprecedented groundball tendencies haven’t abated. Over two-thirds of balls off his bat (67 percent) have been on the ground—by far the highest such figure in the American League. While that’s a slight decline from the 71 percent mark he posted last month, it’s by far the highest of his career and a full 10 points above what he posted from 2002-09.

Meanwhile, his 16 percent HR/FB rate is the highest it’s been since 2005. Coincidentally, the 2005 season was the only other time in his career that his groundball rate hit 60 percent. So basically, the more he puts the ball on the ground, the more likely it is that each fly ball he hits will clear the fences. I’m not sure if that’s really a contradiction, but it’s certainly an odd correlation.

One thing is clear: this isn’t a common trend. This year, Jeter is the only player in the AL who has both a groundball rate over 50 percent and a HR/FB rate over nine percent.

But the more dramatic (and interesting) statistical oddity stems from the collapse of Jeter’s plate discipline.

Over his career, Jeter has been one of the most selective hitters in baseball, hacking at less than 20 percent of balls out of the strike zone. This year, that number has ballooned to 31.3 percent. Simply put, he’s chasing bad pitches. That’s not an insult or a criticism—that’s an indisputable, objective fact.

The sample size isn’t too small to start drawing conclusions. Jeter has seen 288 pitches outside the zone and swung at 90 of them.

As one might expect, this trigger-happy approach has had a negative effect on his walk rate, which, at five percent, is a career low. It’s less than half of the walk rate he posted last year.

Similarly, you’d expect his strikeout rate to shoot up into the stratosphere, right?

Wrong.

While Jeter’s 14 percent whiff rate is a sizable increase from last month’s nine percent figure, it’s still inexplicably lower than it ought to be, given Jeter’s history and his newfound aggressiveness.  How is that possible?

My first thought upon revisiting these numbers was that, in addition to swinging at more pitches off the plate, Jeter was starting to be less discriminatory with pitches thrown in the zone. That made sense, and I was embarrassed that I hadn’t thought of it a month ago.

But it turns out that’s not right either—in fact, it’s actually the opposite. This year, Jeter has chased a career-low 69 percent of balls in the zone, compared to 74 percent for his career. Simply put, Jeter is swinging at more bad pitches and fewer good ones.

I plugged in the numbers and found that, while 80 percent of the pitches he’s swung at since 2002 were good, just 69 percent of balls he’s chased in 2010 would have been called strikes.

And yet, Jeter’s 86 percent contact rate is the best of his career.

This doesn’t make sense.

I’m not insulting Jeter, I’m not criticizing Jeter, and I’m definitely not suggesting that Jeter is using steroids, as I was somehow accused of doing last month. I am merely a fan of baseball statistics who was drawn in by this series of internally inconsistent abnormalities.

Derek Jeter is making the best contact of his career. That’s a fact.

Derek Jeter is swinging at the worst pitches of his career. That’s a fact.

But that Derek Jeter is making the best contact of his career while swinging at the worst pitches of his career—that’s not just a fact, that’s a mystery.