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A further attempt to explain Chris Archer’s ERA-FIP Gap

Why does Archer keep allowing more runs than his balls in play would suggest he should?

New York Yankees v Tampa Bay Rays Photo by Jim McIsaac/Getty Images

The film The Lost City of Z centers around a man, Percy Fawcett (played by professional handsome man, Charlie Hunnam) who is obsessed with finding a probably-not-real lost ancient city in the Amazon. Fawcett is so single-minded in his passion that he devotes his entire life to the undertaking, ignoring his wife and children for the most part until he has a son who is old enough to go with him, and at that point the two “disappear” into the Amazon forever.

I watched that movie on a plane, and it wasn’t that good, to be honest, but it does make me think that I have potentially become the Percy Fawcett of DRays Bay. Instead of chasing ancient cities in Amazon, however, I have been chasing the ERA-FIP gap in Chris Archer’s profile.

I mention this statistical anomaly in nearly every article discussing Archer, but I have yet to find what I believe to be conclusive evidence as to why Archer has seen the gap between his ERA and FIP move in the wrong direction four of the past five seasons:

Archer’s ERA-FIP Over the Years

2013 3.22 4.07 -0.85
2014 3.33 3.39 -0.06
2015 3.23 2.90 0.33
2016 4.02 3.81 0.21
2017 4.07 3.40 0.67

The year is 1923, and my research has piqued the interest of John D. Rockefeller. He’ll be paying for one final expedition into the jungles of the Amazon MLB Dark Web of Brooks Baseball, BP, and FanGraphs. If I don’t make it out alive, tell my wife and kids I love them - in like a two-minute scene, max. Hope you have your expedition gear with you.

Small Sample Size Caveat

Let’s get this out of the way to start, since I know it is the theory many of you will hold onto throughout. Yes, we are dealing with a five-season sample that just so happens to trend in a certain direction.It is admittedly possible that it is pure coincidence that his ERA-FIP gap has devolved in each full season, and looking at his career as a whole, it’s not as if the 0.20 gap between his ERA and FIP is some astronomical chasm.

However, I do think the trend from the chart above is at least worth digging into further. Will we come to a one million percent statistically accurate conclusion? No. The author just used “one million percent statistically accurate” in a sentence - clearly we’re not. However, I do think you’ll find at least a point or two interesting along the way.

Theory No. 1: The Juiced Ball

Whenever any trend makes its shift right around the 2015 season, it’s hard not to wonder what impact the (almost certainly) juiced ball has had on that trend.

Here are some numbers from the past five years for Archer, keeping in mind that the 2015 All-Star Break is the assumed time when a possible change was made to the baseballs:

The jump in fly balls leaving the yard is noticeable, but so is the jump in hard contact and fly balls in general that Archer has allowed over the past two and a half seasons. It’s also certainly worth looking at the league-wide jumps over that same time period:

League-wide Changes

Time HR/9 FB% HR/FB% Hard%
Time HR/9 FB% HR/FB% Hard%
2013-2015 ASG 0.9 34.2 10.2 29.3
2015 ASG-2017 1.2 34.9 13.0 31.1
Difference 0.3 0.7 2.8 1.8

So there would league-wide boosts in all four of the same categories, but certainly not to the extent that Archer saw. I think we can say that whatever is going on with the ball (as well as more batters tinkering with their launch angle) has had some impact on Archer, but I’m not sure there’s anything there that suggests it explains the ERA-FIP gap. At least not entirely. It is indeed interesting that if we use xFIP instead of FIP, the difference is even starker. It’s not a trend, but a full-blown pattern, with the difference between his ERA and xFIP getting worse in each of the past five seasons.

Theory No. 2: Command Slipping

This theory jumped to mind when I was studying for my fantasy baseball draft and looking at the numbers for Robbie Ray. Ray is a singular case study, but he did see his ERA plummet from 4.90 to 2.89 from 2016 to 2017, despite his FIP staying nearly identical (3.76 in 2016 and 3.72 in 2017). Considering they still hand out wins for actual run suppression, this is the sort of change Rays fans would love to see.

Given that the knock on Ray was often his command, I decided to head over to Baseball Prospectus’ Command rankings to take a look at where Archer ranked in that regard.

Low and behold, there were only 19 pitchers with at least 150 innings last season who ranked worse than Archer in terms of BP’s Command Metric. For the uninitiated, this metric basically tries to quantify how strong a pitcher is at avoiding the heart of the plate, while also looking at a pitcher’s ability to hit his spots.

Here’s the heat map for Archer in 2017, from Baseball Savant:

Well, we can certainly say Archer isn’t afraid to attack the hitter. But maybe he’s a bit too unafraid. That’s a lot of dark red right in the middle of the plate. Here’s a comparison to Kyle Hendricks of the Cubs, a noted command expert and one of the pitchers who has been best at beating his FIP over the past few seasons:

That’s a noticeable difference. Hendricks lives a lot closer to the corners than Archer, and that could have a noticeable effect on the type of contact each pitcher allows. Quality of contact allowed is basically the kryptonite to FIP, so maybe we have our answer.

Can you smell that “but” coming, though?

Here are Archer’s command ranks for his entire career:

Archer’s Command Ranks

Year ERA FIP ERA-FIP Command Percentile
Year ERA FIP ERA-FIP Command Percentile
2013 3.22 4.07 -0.85 4.8
2014 3.33 3.39 -0.06 5.9
2015 3.23 2.90 0.33 3.4
2016 4.02 3.81 0.21 6.0
2017 4.07 3.40 0.67 26.7

Archer has never been a command specialist. Even earlier in his career, when he was beating his FIP, he did so despite some of the worst command ranks in all of baseball.

However, I don’t the two are totally unrelated. This was entitled Theory No. 2, but in reality it can very closely tied to Theory No. 1. If Archer is leaving the ball over the middle of the plate more frequently, and you combine that with hitters emphasizing launch angle and the balls maybe sporting seams that favor a few more feet of distance on fly balls, suddenly it’s no wonder Archer has seen his runs allowed increase over the past two and a half seasons. When hitters weren’t emphasizing launch angle quite as much, and the ball wasn’t flying out quite as far, Archer’s command flaw was a little easier to hide. Nowadays, not as much.

That being said, I still don’t think it explains the difference entirely. I think there’s one more piece, a third heat to this issue, that has made a decent impact.

Theory No. 3: Lack of a Third Pitch

Take a look at Archer’s pitch usage chart for his career:

While Archer’s sinker was never massively different from his fastball, it is interesting that he dropped it out of his repertoire right around the time the ERA-FIP gap appeared. To tie Archer to Ray once more, Ray notably added a curveball to his repertoire last season, the same season he was able to beat his FIP instead of the other way around. While comparing to a sample of one is dangerous, the logic makes sense.

If hitters are guessing more to go big on pitches, a 33 percent chance is way worse than a 50 percent chance. If Archer can simply begin to lean on that change up 15 percent of the time instead of 7-8 percent, the difference could be huge.

The good news is that Archer may be looking to do just that, and rely on his change up in 2018. As he told’s Glenn Sattell after one spring outing:

“I was able to face a really good team, get a lot of outs and get outs in ways I typically wouldn’t. Lot of changeups, got a lot of good feedback. Not all of them were strikes, but high-quality pitches.”

Spring training is the time for pitchers to experiment, and it’s a great sign that Archer elected to experiment with using his change up yet again. Hopefully that pitch finally hits its stride, and some of the success and feel he found this spring can roll over to the regular season.

* * *

So have we found the Lost City of Z? I’m not sure. It seems as if theory tossed out in this article has played a role in the trend that has appeared over the past five seasons. Archer’s relative lack of command was never going to mix well with the changes going on throughout baseball, and when you add on the fact that he dropped down to basically a fastball-slider pitcher right around the same time, suddenly it doesn’t seem like such a fluke that his actual runs allowed (ERA) have been higher than what his balls in play might imply he should have allowed (FIP).

If Archer can up that changeup usage just a bit this season, and continue the other trend of improving his command ranking that he began last season, he may just be able to halt the slow trend towards a higher and higher ERA that has occurred over these past five seasons.

Of course, if he is able to make those changes, and the trend still continues, I may end up with Percy Fawcett lost somewhere in the Amazon.