Thanks to our friends at Baseball Info Solutions, we have batted ball information dating back to 2002, which gives us data on 11 full seasons and 60% of the 2013 season. It might not be quite as catchy of a time frame as the “Dead Ball Era” or “Steroid Era”, but it’s our own little stretch of baseball that we care about. Sometimes I refer to it as the “UZR era”, since that’s one of the more common stats cited that uses batted ball data, but other stats have the same timeframe here on the site.

One of the more common batted ball stats cited around here is HR/FB ratio, as the data has shown to be not particularly predictive, yet can have a huge impact on a pitcher’s results. If he’s giving up fly balls that are staying in the yard, that can lead to very good results — hello, Matt Cain and Jered Weaver — but those results can also be kind of fickle, as 2013 Matt Cain is demonstrating with aplomb.

Still, despite the inconsistent nature of seasonal HR/FB ratio, we have enough data to establish some norms for Major League pitchers. From 2002 to 2012, only one pitcher in Major League history had thrown 100 innings in a season and allowed fewer than 4.0% of their fly balls to leave the yard; that pitcher was, of course, Matt Cain, in 2011. 2011 Cain represented a pretty realistic floor, as it was the best HR/FB season from the biggest HR/FB outlier in the game.

Okay, so Cain’s 3.7% HR/FB ratio isn’t held in quite the same esteem as Joe DiMaggio‘s 56 game hitting streak or Cal Ripken’s 2,632 consecutive games played, but hey, it’s still a record. A FanGraphs record, sure, but I have no problem counting it as a record, since I write for FanGraphs and all. It might not be the most prestigious record on the books, but it’s still a mark that represents a pretty neat accomplishment.

It’s also an accomplishment that is currently under fire from one of the least likely sources on the planet. Right now, Jhoulys Chacin has a 2.8% HR/FB ratio in 120 innings pitched, making it the best season by that mark since BIS started tracking batted ball data. That list includes 1,654 pitcher seasons of at least 100 innings. Not a single one of those 1,653 other seasons has resulted in a lower HR/FB ratio than what Chacin is posting right now.

Jhoulys Chacin pitches in Colorado.

Even with the humidor, Coors Field is still one of the most homer friendly ballpark in the Majors. Our data has the park with a home run factor of 114, meaning that a pitcher for the Rockies would be expected to post a home run rate 14% higher than they would pitching for a team that plays its home games in a neutral ballpark. The humidor has offset some of the effects of playing at altitude, but it hasn’t eliminated them entirely. And so Chacin is making a run at posting the lowest HR/FB ratio in recorded history while playing half of his games in a ballpark that specializes in turning fly balls into home runs.

Perhaps most amazing is that Chacin hasn’t really demonstrated any kind of special home run prevention skills prior to this season. Coming into the 2013 season, 10.9% of his fly balls had gone over the fence, pretty much in line with what you’d expect from a Rockies starter. He’s not a fly ball pitcher who gets a ton of infield popups, as other HR/FB outlier pitchers are. He doesn’t get a ton of strikeouts either, which has been identified as a marker of a pitcher who can post a slightly lower than average rate of homers on fly balls. He’s not left-handed, he doesn’t throw the knuckleball, and he doesn’t play in an extreme pitchers park.

If you had been told before the season started that a Major League starting pitcher was going to make a run at posting the best HR/FB ratio in the last 12 years, Chacin might have been one of the very last people you took. Joe Blanton probably would have been the very last, but Chacin would have been standing around looking at Blanton when everyone took their final picks. And yet, here we are, and after 19 starts, he’s allowed just three home runs. Kelvin Herrera gave up as many home runs in one appearance — which lasted 2/3 of an inning and involved him facing six batters — as Chacin has while facing 493 batters all year.

You might say “aha, more proof that steroids testing is working, and driving all the power hitters out of the game”, except the average NL pitcher is giving up home runs on 10.3% of his fly balls this year, which is right in the same range it has been since the data started getting collected. There’s no real evidence that contacted balls are flying over the fence at a reduced rate now than they used to; there are just fewer contacted balls. Chacin, though, isn’t one of the pitchers driving up the league’s strikeout rate. He’s a pitch-to-contact guy, and he’s a pitch-to-contact guy in a ballpark where contact is most harmful.

You probably don’t need me to tell you that Chacin is unlikely to keep this up. There’s outlier performances, and then there’s this. There’s still two months to go, so odds are good that Cain’s record will stand by the time Chacin finishes the season. But it’s kind of incredible that we’re even talking about this. Jhoulys Chacin pitches in Colorado, and he pitches to contact, and he’s not giving up home runs.

Baseball.