Last season, it looked like Julio Teheran had finally turned the corner.
The perpetual Braves top prospect had already put up one great season, posting a 2.89 ERA in 33 starts in 2014 but he took a big step back in 2015, posting a 4.04 ERA and a career-worst 4.40 FIP. But 2016 was different, Teheran came out looking like an ace with a 2.46 ERA through the end of June.
While his second half wasn’t nearly as good — a 4.14 ERA in 14 starts — he finished with a very impressive 3.21 ERA.
That left the Braves with a choice this offseason, to either trade someone who could be their future ace or to hold on to him. Ultimately, the John Copollela-led front office opted to keep Teheran as a push to give fans something worth watching in the inaugural season of SunTrust Park in 2017.
Anyone who has followed Teheran’s 2017 season can see the irony in that.
Teheran has been abysmal. In 14 starts, he’s posted a career-worst 4.86 ERA. To be fair, Copollela and company got it half right. He’s sure been fun to watch at home if you like home runs and are a fan of the other team. In seven home starts, Teheran has posted a 7.25 ERA.
Now some of that can be attributed to a career high homers-per-fly-ball rate (15.1 percent) and to the launching pad nature of SunTrust Park. Of his 16 home runs this season, 10 have come in the new Cobb County ballpark despite the fact that he’s actually thrown 7.2 more innings on the road.
But there’s a bigger underlying problem behind Teheran’s home/road splits that needs to be looked at:
If the big bold letters didn’t do it for you, Teheran is walking a lot more guys at home than he is on the road. A lot.
His career walk mark is 2.5 BB/9, which indicates that he’s walking more batters in general both at home and on the road, but the 4.5 BB/9 is absurdly high; nearly twice his career walk rate.
But why is that?
Well to get to the bottom of that, we need to go a little further into the splits.
While he has walked a lot of lefties both at home and on the road, his 7.6 walk rate against lefties at home is astronomically high. Just for fun, if you take away Teheran’s performance against left-handed hitters at home this season, this is the pitcher you’d be looking at:
But that’s weird, right? Why on earth would that kind of split create such a drastic difference in performance? Don’t worry, readers of Big Time Atlanta Sports, I wouldn’t take you this far without bringing this full circle.
So I’ll bring you the good news first — Teheran’s problem isn’t really his fault. The bad news? I don’t know how you fix it.
Teheran’s problem is simple and kind of weird — he’s getting squeezed by umpires.
Let’s take a look at a couple of heat maps to drive this point home (click to increase the size):
On the left, we have Teheran’s typical pitch location vs. left-handed batters this season. Notice how he clusters pitches low and away, even nibbling off the plate quite a bit. The heat map on the right is Teheran’s strike percentage against lefties. Notice how Teheran seemingly isn’t getting a high percentage of strikes on the outer sixth of the plate, considering that is, in fact, a strike. He’s getting even less help just off the plate, which is fine considering that is, in fact, not a strike.
But we need to establish whether or not this is abnormal. So for comparison’s sake here are the strike percentage heat maps versus lefties for two right-handed pitchers — Max Scherzer and Jeremy Hellickson.
Notice that both guys are getting significantly more generous outside corners against left-handed hitters. While Teheran gets just one portion of the outer sixth more than 78 percent of the time, Scherzer is getting almost the entire outer sixth at more than 80 percent of the time, and this comes in spite of the fact that Scherzer utilizes the inside corner far more than Teheran.
It’s also worth noting that Scherzer is among the game’s best pitchers and umpires are sure to give him a little extra leeway on those borderline pitches. That’s why I included a guy like Hellickson as well, who is a good comp because he likes to go low and away to lefties and his career 2.75 BB/9 rate is comparable to Teheran. While Hellickson doesn’t get a Scherzer-esque zone, he’s definitely getting a more generous zone on most of the outside corner and even a little bit off the zone.
And just for good measure, I’ll do one last comparison with a mystery pitcher:
That’s an incredibly generous strike zone on the outer sixth of the plate, and it certainly looks like a zone given to one of the game’s best pitchers. Teheran is certainly pining for that kind of zone these days, and for good reason — that’s Teheran’s strike percentage by location versus left-handed hitters from his debut in 2011 through his last start in 2016. Talk about a stark contrast.
That trend is actually exacerbated once you factor out pitches that batters actually swung at and just look at what percentage of pitches that aren’t swung at are being called strikes. Here’s the side-by-side for Teheran from 2011-2016 (left) compared to his 2017 numbers (right).
For parts of five seasons that Teheran pitched before 2017, he got a majority of the outer sixth of the zone at least 75 percent of the time. This year, he’s not getting a single zone called more than 71 percent of the time.
When this happens, Teheran is forced to pitch with five-sixths of a strike zone. And even more damaging, there’s absolutely no sense in trying to get a lefty chasing beyond the outside edge when you aren’t even getting the outer sixth. While a sixth of a strike zone doesn’t feel like a lot, this illustrates why it matters a lot:
That heat map illustrates opponents’ slugging percentage based on pitch location. When opponents are putting those low and away pitches in play, they’re turning into outs and they’re certainly not turning into homers. By taking away that part of the strike zone, Teheran is being forced into throwing pitches in a part of the strike zone that batters can barrel up.
So just to recap, here’s what we’ve addressed so far — Teheran isn’t getting the outside corner of the zone against lefties, even compared to other pitchers this season. This is leading to A) a higher walk rate against lefties and B) more pitches being thrown into parts of the strike zone that hitters can make hard contact on, resulting in a higher slugging percentage.
But a piece of this puzzle is missing: why is Teheran actually pitching pretty well against lefties, outside of walk rate, on the road? Is SunTrust Park creating some kind of innate bias against Teheran?
Since there isn’t a way to create home and road heatmaps, I’ll have to do it the old fashioned way. Here are the individual heat maps from each of his seven home starts:
It’s worth noting that the strike zone in the second game on April 14 where he got no part of the outside corner more than 35 percent of the time was abysmal and that game was among his worst — a four-inning, seven-run performance with three walks. Equally interesting is the May 24 game against Pittsburgh, in which Teheran got the outside corner 100 percent of the time and promptly allowed three unearned runs in six innings with six strikeouts in one of his best performances of the season.
In general, there were a few starts in there where he received a pretty fair zone but by and large, the outside corner was not a given strike. Now let’s compare those with his seven road starts this season:
This certainly looks a lot better. While there are a couple of outliers — May 13 and his most recent start on June 14 — it looks as if Teheran is definitely getting more calls against lefties on the outside corner.
Through all of that, we’ve established what Teheran’s problem is, but why?
Could catcher Tyler Flowers be costing Teheran strikes? That’s incredibly unlikely. According to StatCorner, which tracks catcher framing statistics, Flowers has the 11th-lowest percentage of pitches in the strike zone called a ball among catchers with at least 1,000 pitches caught this season. He also ranks at the top of the league with 12.4 percent of pitches outside the zone being called a strike, and he’s the No. 1 overall catcher by StatCorner’s runs above average metric netting the Braves 13.1 runs based on his ability to frame pitches. While Kurt Suzuki is nowhere near as good a pitch receiver as Flowers, he’s only caught Teheran twice, in his two most recent starts, and even then he’s been essentially a wash behind the plate at 1.0 runs below average.
So that leaves SunTrust Park. Could that be the culprit behind Teheran’s struggles against lefties? Could there be something in the outfield that distracts the umpires while a lefty is in the box?
That’s a heck of a lot harder to quantify and can really only be done through comparison. You have to eliminate Jaime Garcia, a lefty, R.A. Dickey, a knuckleballer, and Bartolo Colon, an all-around awful pitcher this season, from a true comparison. That leaves Mike Foltynewicz:
And sure enough, Foltynewicz has an extremely high ERA versus lefties at home despite the fact that he’s actually pitching worse overall in terms of batting average and slugging against lefties on the road. This can be almost entirely explained by a walk rate that is nearly twice his walk rate against lefties on the road and nearly three times his walk rate against righties at home.
Is this enough to explain Teheran’s struggles? Probably not, but it’s certainly worth looking into.
Now how do we fix it? I’m not really sure. Educating umpires might be step one, especially if there’s some kind of bias that exists against Teheran that doesn’t exist against other pitchers, then it probably needs to be brought to their attention. So if you’re feeling really ambitious, maybe share this article with the MLB Umpires’ Association.
But until then, the Braves might be best trying to get Teheran more starts on the road.