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Carlos Rodón, ace?

The southpaw started hot and ended cool, and for a guy who couldn’t raise his arm above his head after 2017, that ain’t bad

MLB: Chicago White Sox at Minnesota Twins
Out of Gas: Rodón’s abysmal September left a mark in the minds of Sox fans.
Brad Rempel-USA TODAY Sports

Looking at Carlos Rodón’s overall 2018 statistics, it’s hard to be impressed.

The numbers sing a sorry song, starting with a career low in K/9 at 6.71, and no improvement in walks (4.10 BB/9). Clear issues in commanding the strike zone led to a professional career high (including the minors) in fly balls allowed, at 42.9%. The 2018 season was the first in Rodón’s professional career where he allowed more fly balls than grounders, leading to career worsts in ERA, FIP and xFIP.

It also does not help that Rodón ended the season in a massive slump. In the month of September, Rodón had the same amount of K/9 as BB/9, at 6.26. He averaged a 31 game score, topping out at just 55, and had a 9.22 ERA and 6.78 FIP. Simply, Rodón’s September was atrocious.

Now, what gets lost sometimes is that Rodón came into the season rehabbing after a major surgery on his throwing shoulder. Before the season, Rodón just getting through the year healthy would have made 2018 successful season — and he did that. What is more impressive is that Rodón was actually very good for most of the season.

Here is Rodon’s ISO on all pitches in September:

Rodon’s ISO in September, all pitches.

That’s a lot of red — not just in the strike zone, but below. That’s not good at all, as teams were crushing Rodón. However, even though he was better before September, good contact was still prevalent:

Rodon’s ISO through August, all pitches.

Rodón’s problem, even before September, was that hitters were seeing his pitches well. And yet his .218 batting average against in 2018 was actually a career best, by over 30 points. Huh? Well, Rodón was not allowing many hits, but when he did, those hits were with good contact and lift. Rodón allowed a career high in launch angle (16.7 degrees), which helped translate to his career high in fly ball rate and pull percentage. It was a perfect storm, which drenched Rodón in September, as he was walking more batters and allowing better contact. That usually equates to runs — and it definitely did in his case.

So yeah, maybe Rodón’s overall season was not ace-like. But it was ridiculous to expect him to be after major shoulder surgery.

However — here is where the good stuff really starts — his slider through August was elite, and his fastball through August was one of the best fastballs among all starting pitchers.

Let’s start with the slider. According to pitch info, Rodón’s slider had a pitch value of 2.51 through August, making it the eighth best slider among starting pitchers. His slider was used about a quarter of the time, and it was clearly his best pitch all year.

Wanna see something cool? Look at is this heat map:

Rodón’s slider through August ISO.

Rodón’s fastball, though not as effective as the slider, was thrown about half of the time. So if the fastball was there, Rodón had a good game. Through August, Rodón’s fastball had a 1.84 pitch value, making it the best fastball in the majors among starting pitchers. That is why Rodón was much better before September, with an average game score of 61.

So in the last month of his season, in a year when he missed the first two months recovering from major shoulder surgery, Rodón’s fastball faltered. It went from the best fastball among starters in all of baseball to the worst, with a -4.87 pitch value.

Rodón’s fastball in September ISO.

That’s bad.

For the entire year, Rodón relied heavily on his fastball, much more than usual, even when healthy. In 2017, he threw his fastball 37.1% of the time, and 40.6% of the time in 2016. It was probably not wise to increase fastball usage by 10% after coming off shoulder surgery, but Rodón needed it. It didn’t help that Rodón’s sinker was by far his worst pitch in 2018, and its usage fell 14%. That helped force Rodón to use his fastball too often, and he was understandably gassed by the end of the season.

So, is Rodón an ace? Not yet. But he proved he had two of the best pitches among starters in an injury-shortened year, which is pretty impressive. Sure, Rodón wasn’t dominant through his last pitch of the season, but shoulder injuries are serious, and he was able to rebound for much of his season.

Imagine what will happen after his first offseason after surgery, pitching in 2019 without coming off of an injury. Rodón may not be an ace yet — but he is closer than he was last year.