Atlanta’s ace, Julio Teheran, has a career 3.34 ERA, a good mark even for this pitching-friendly era. This year’s numbers, at least in some ways, are the best of his career. He’s a 25-year-old with less than $30 million in guaranteed money remaining on his contract, which runs through 2020 if you count the low-cost team option for that season. If the Braves make him available before the deadline, he’d instantly become one of the most valuable assets on the market.

But is Teheran an ace, like the Braves are likely to price him? Or is he more of a good pitcher on a nice run? Since assuming regular major-league duties in 2013, he’s 44th in pitching Wins Above Replacement despite being 11th in innings pitched, as he’s accrued value by staying healthy and racking up innings, but not dominating in the traditional walk, strikeout, and home run categories.

But this year, once again, Teheran is dealing, and he’s doing so without strikeout, walk, or home-run rates that would appear on the first page of each leaderboard. For teams hoping to acquire the Braves ace, they’ve got to be wondering who he will be on their team; the guy who looks great by ERA or the guy who looks like an innings-eater by FIP?

It’s instructive to look at his ranks in a few categories. Let’s start with the main factors included in the more popular ERA estimators. In the interest of smoothing over some of the peaks and valleys of his career, let’s establish 2013 as the beginning point for this investigation.

Julio Teheran, Ranked In a Few Key Categories Stat Value Rank K% 21.5% 42 BB% 6.7% 61 K-BB% 14.8% 42 HR/9 1.07 96 GB% 37.8% 125 Since 2013, qualified starters, n=140.

Teheran has made it this far with slightly above-average strikeout and walk rates, but considering that his ERA over that time frame ranks 30th, the peripherals don’t match the outcomes. So let’s venture further afield. There are plenty of stats that inform projection systems which don’t show up in all of our ERA estimators, so let’s throw these into the mix and see if something pops.

Julio Teheran, Ranked in Ancillary Categories Stat Value Rank FB Velo 90.9 90 PU% 4.3% 22 BABIP 0.271 9 Soft% 17.2% 81 Ideal Angle Exit Velo 92.4 93 Since 2013, qualified starters, n=140.

PU% = IFFB*FB, or pop-ups divided by balls in play. Average = 3.4%

Ideal launch angles (10-30 degrees) are best for homers and line drives.

Now here are a couple things that stand out. Like pop ups. And batting average on balls in play. He’s been good at those things, and they can drive a good ERA.

The spread on pop ups isn’t very large, though. First-best (Chris Young) is separated from 140th-best (Jaime Garcia) by 6.5 percentage points. Still, the pop-up figure helps explain Teheran’s small BABIP number. If we gave Teheran a league-average pop-up rate since 2013, we’d have to put 68 more hits on his ledger, and his BABIP would soar to .301, or basically league average.

Even though the spread isn’t huge, pop-up rate (pop ups divided by all balls in play) is decently sticky year to year. It has a 0.63 year-to-year correlation, which is much better than the 0.49 number for home runs. In other words, you would make a safer bet to bet on Teheran to continue getting more pop ups than if you bet on him to continue giving up more homers than average. Re-rank Teheran for strikeouts plus pop ups minus walks, and there he is at 32nd in our sample, in line with his ERA. Just outside the top 30 again, though.

On the other hand, given that Teheran has below-average velocity for a righty and lives high in the zone for those pop ups, it’s probably also true that he will continue giving up homers. Derek Carty found that it takes 2.7 years for home-run rate to stabilize, and we’ve got those years for Teheran, too. You can’t ignore the home runs.

And let’s not forget that pop ups are now included in pitching WAR as an automatic out, equal to a strikeout. So a FIP-based WAR isn’t ignoring the pop-ups; he’s getting credit for those.

But when you look at FIP alone, you see the huge gap, with a 54 point gap between his ERA and FIP, thanks in part to all those popups. But how much of that gap should we expect to continue going forward?

Let’s look at pitchers similar to Teheran based on this ability to induce pop-ups. The top 10% in pop-ups since we started tracking the stat in 2007 have had ERAs that were 1% better than league average, while their FIPs have been 5% worse. That’s not Teheran-like — his career gap is 15 percentage points — but let’s look at the guys that have had 600-inning FIP and ERA gaps with great pop-ups, and what they did during and after that stretch.

There are 22 pitchers that have achieved three years of an FIP-ERA gap over 0.4 with a pop-up rate over 4%. Ten of them appeared on the list once and never returned. But we can look at the 19 not named Julio Teheran, Noah Lowry, or Wei-Yin Chen and see how they faired the next three years after they first showed up on the list.

Pop-Up Heavy FIP-Beaters, Before and After Time Frame Ave IP Weighted PU Weighted ERA Weighted FIP Weighted Diff During Stretch 598 5.0% 3.68 4.24 -0.56 After 446 4.8% 4.22 4.44 -0.22 Minimum 600 IP during FIP-beating stretch.

Minimum -0.4 ERA-FIP.

Minium 4% pop-up rate.

n in both buckets = 19

Would you look at that. The pitchers got worse, but, as a group, they maintained a noticeable gap between their ERA and FIP. And of course they were going to get worse — they got older! Some of that regression was simply age-related decline, while Teheran is still young. But it is worth noting that they didn’t sustain the same size gap that they posted during their initial run.

The pitchers that fell apart and had a worse ERA than FIP were either near the end of their careers (Al Leiter, Russ Ortiz, and Hideo Nomo) or started to lose their ability to get pop-ups at the rate that would include them in the sample (Ramon Ortiz, Randy Wolf, and Jeremy Hellickson).

Jake Peavy is probably the best comp for Teheran on the list, once you consider age, quality, and arsenal. He had a 3.69 FIP, 3.13 ERA, and a 4.2% pop-up rate built mostly on good command and a great slider. Matt Cain is another good one (3.43 ERA, 3.86 FIP, 4.6% pop-ups). Cain and Peavy both both had stellar ERAs in their next three seasons, which provides a lot of hope for Teheran boosters. There are examples on both sides of the argument.

It is worth mentioning that those pitchers remained in their own home parks for those next three seasons, though. And that the last Brave righty with similar stats didn’t survive a park change, or hasn’t so far. Shelby Miller (3.27 ERA, 3.87 FIP, 4.0% pop-ups) has had mechanical problems, and his arsenal is fairly different, but he makes our ‘before’ list, and the after doesn’t look great.

As long as Teheran maintains his ability to get the pop-up, he should be fine, even if maybe not quite as good as his ERA would suggest. And if you look at pitchers most like Julio Teheran — pitchers with a three-year demonstrated ability to get the pop-up — they’re at least a good bet for the next three years. Even more so when you consider the Braves righty is only 25 years old. Here’s the whole table of comparable pitchers.

If we assume that Teheran’s youth will allow him to regress less than most of these guys, maybe his true-talent ERA gap is something like 0.3 runs per nine innings, and with a ~3.90 FIP projection, that would put him as a 3.60 ERA guy going forward, in the NL anyway. It’s a little closer to 4.00 in the AL, once you adjust for league quality and the DH.

That’s not a dominating frontline starter, but given Teheran’s youth and controllable years, he remains a very valuable piece. He’s not likely to keep beating his FIP by this degree, but he is likely to keep beating it by a decent margin, and that makes him a quality mid-rotation arm. A team shouldn’t pay ace prices to land Teheran based on his ERA, but he’s a good pitcher on a great contract, and so the line for his services will be quite long.