Julio Teheran is an Outlier.

Note: All statistics used in this piece come from FanGraphs.

Major League Baseball defines a “qualifying” pitcher (one eligible for the ERA title) as one who threw at least one inning per every game of the season. Back when the season was 154 games long, this meant pitchers had to throw 154 innings. Today, the line is 162.

Over the last six seasons, only six pitchers have reached that threshold every single year.

They’re an interesting mix.

There are the obvious ones—the workhorses, Jon Lester and Max Scherzer, who have reached the threshold in eleven and ten straight seasons, respectively.

There’s Jose Quintana, younger than Lester and Scherzer, but of a similar ilk since his first full major league season in 2013.

There’s Rick Porcello, not at the top of the list of the league’s best pitchers, but impressively durable, with a Cy Young to his name amid ten straight seasons above the line.

There’s Mike Leake, a bit of a journeyman of late, undersized and consistent, with only one 200-inning season but eight straight as a qualifier.

And then there’s Julio Teheran.

Teheran, you might argue, is as much of an outlier on this strange little list as Leake. Or Porcello or Quintana, even. Which is probably fair. It’s a small list. Everyone’s an outlier on a small list. But when I headlined this “Julio Teheran is an Outlier,” I wasn’t talking about him within the context of this list. I was talking about him within baseball as a whole.

If you possess at least a moderate level of interest in sabermetrics, you’re likely familiar with FIP, a metric first developed by Voros McCracken at Baseball Prospectus nearly two decades ago that rates pitchers on the same scale as ERA, but ignores timing and what happens on balls in play, adjusting those results to the league average. Its calling card is that it’s more predictive of future ERA than ERA is, making it a valuable tool in evaluating how good a pitcher really is, independent of results on the scoreboard.

If we expand our list from above to pitchers who have “qualified” in at least four of the last six seasons, we get 33 pitchers, which is still a small sample, but is fairly robust in a world in which only 57 pitchers reached the threshold last year.

Here’s where Teheran’s odd.

Over the course of his career, going from a promising rookie on a bad team to a back-of-the-rotation-starter on a contending team, seemingly barely holding onto a job as 2019 rolls forward, the gap between Teheran’s ERA and FIP in qualifying seasons has held steadier than any of those other frequent qualifiers. Year over year, Teheran’s “luck”—as we might call the gap between actual earned run results and what they should be, given what a pitcher can theoretically control—has been more consistent than that of anyone else with a comparable sample.

Standard Deviation of FIP/ERA gap across qualifying seasons, 2013-2018, pitchers who qualified in four or more seasons

And while that might not be spectacularly abnormal (someone has to lead that category), here’s what’s truly strange:

Teheran also has the largest such gap, on average, and it’s a gap in which his ERA consistently outperforms his FIP.

Average FIP/ERA gap across qualifying seasons, 2013-2018, pitchers who qualified in four or more seasons

(positive numbers = ERA better than FIP)

Teheran, at the head of the pack in seemingly good luck, has also experienced that luck with more consistency than any other starting pitcher in his realm of durability.

So, the question goes, is Julio Teheran actually better than his FIP indicates, or has he simply been lucky?

The biggest contributing factor to this seems to be Teheran’s opposing BABIP of .269 between 2013 and 2018, which was the fifth-lowest in the MLB among the 104 pitchers who averaged more than 100 innings pitched across those seasons. Statistically speaking, this means Teheran saw a higher portion of balls put in play against him turn into outs than all but four other comparable pitchers. Why was this? Did Teheran experience exceptionally good defense?

Braves pitchers as a whole enjoyed the twelfth-best opposing BABIP from 2013 to 2018, and Fangraphs’calculation of the Braves’ defensive runs above average over that period ranked sixth in the MLB. Better than average. Not spectacular.

But the man with the next-most innings pitched for the Braves over that period, Mike Foltynewicz, has an opposing BABIP of .302, while Teheran’s sits at .269. And the quality of the contact against these two pitchers is strikingly similar, as Teheran allowed hard contact 31.8% of the time to Foltynewicz’s 31.3%, and soft contact 18.3% of the time to Foltynewicz’s 18.2%.

In terms of the trajectory of batted balls against Teheran, he’s a fly ball pitcher, provoking flies on 40.8% of batted balls between 2013 and 2018 (13^th-most in the MLB among the 104 pitchers who averaged more than 100 IP over those years), but he’s hardly above average in provoking pop-ups, which are almost uniformly outs (his infield FB% sits at 10.1%, close to the league average). Teheran doesn’t feast off pop-outs as, say, R.A. Dickey did (13.4% IFFB%). And again, his profile isn’t all that different from that of his teammate Foltynewicz, (FB% of 38.4%, IFFB% of 10.0%), making the BABIP gap all the more puzzling. They’re right-handed pitchers on the same team. They should be facing similar lineups. They should have the same defense. Their BABIP’s should work out similarly. They don’t.

At this depth, as far as balls in play go, we’re stumped. But FIP also controls for timing. So how does timing impact all this?

Teheran’s LOB% sits at 76.0% over those six seasons, good for 17^th in the league among those 104 pitchers with more than 100 IP per year. Nothing extraordinary—he wasn’t stranding runners at the rate Clayton Kershaw was—but certainly a factor. Teheran is undercutting FIP on both aspects for which it controls.

Overall, it seems there are a few possibilities, some of which could be explored further with deeper dives into lineups and batted ball cross sections.

• The Braves have played better defense when Teheran is on the mound.
• The Braves have played stronger defensive lineups when Teheran’s pitched.
• There’s something about contact quality on Teheran’s fly balls, ground balls, etc. driving the low BABIP (his HR/FB ratio is close to the league average over those six years, which suggests this isn’t the case, but it’s possible there’s something lurking in that cross section).
• Teheran himself plays spectacular defense (he does have the fourth-most defensive runs saved as a pitcher over the six seasons, but those have a negligible impact on BABIP given a pitcher’s role in a defense).
• Teheran is consistently lucky.
• Teheran is a wizard capable of directing baseballs into gloves just frequently enough to keep himself in a starting rotation, but not enough to be a perennial all-star.

Through seven starts this year, things have flipped for Teheran. He’s posting a 5.01 FIP and a 5.35 ERA, suggesting that for the first time in his career, he’s getting a bit unlucky.

This supports the hypothesis that Teheran really has just been lucky the whole time. After all, six seasons isn’t a huge sample, even if those six seasons consist of well over 1,000 innings. But with over three quarters of the season to be played, if Teheran does possess some hidden advantage, there’s plenty of time for him to turn things around.

At the very least, it’s possible.