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The Next Step: White Sox starters

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Carlos Rodón, Reynaldo López, and Lucas Giolito lead a young core group that has underwhelmed thus far. What do we need to see from each in 2019?

MLB: Chicago White Sox at Minnesota Twins
No. 1 in waiting: The former 3rd overall pick has been tabbed a future ace for years, but hasn’t realized his potential yet.
Brad Rempel-USA TODAY Sports

When the Sox embarked on the teardown, trading Chris Sale, Adam Eaton and Jose Quintana, fans and experts loved the haul they received for each trade. Along with a young controllable starter they already had in Carlos Rodon, the additions of Lucas Giolito, Reynaldo Lopez, Michael Kopech, and Dylan Cease looked like a great pitching foundation for the rebuild. However, Rodon, Giolito, and Lopez have not yet realized their potential, while Kopech had Tommy John surgery in 2018 and Cease is still in the minors.

We know that all of the above pitchers need to take steps forward this year. But what exactly should fans look for — what defines a “step forward?” Well, let’s find out.


Carlos Rodón: Regain a fastball or sinker

The point of this series is to avoid clichés, and Carlos Rodon has an obvious one: With a healthy offseason, he should be off and running in 2019.

Of course this is somewhat true, but it does not really tell the whole story. With using Pitch Info’s pitch values per 100 pitches, Rodon has had only one season where he ended the year when more than one pitch was a positive value — his rookie season in 2015. Every other season, Rodón has had only one positive pitch. That inconsistency really caught up to him in 2018, especially late in the year.

Pitch Info says that in 2018, Rodon had the lowest percentage of pitches inside the zone since his rookie season (46.9%). That mark was the 40th-lowest in baseball last year (min. 120 innings pitched). Now, a low total of pitches inside the zone does not indicate how bad a pitcher was; for instance, Patrick Corbin had the lowest percentage of pitches inside the zone in all of baseball, and he just signed a six-year, $140 million deal.

What is bad for Rodon is that his outside the zone swing rate (27%) is exceptionally low for the amount of pitches he left outside the zone. In the same leaderboard page, from 31st to 60th in terms of zone percentage, only two players had a lower mark than Rodon in outside-the-zone swing rate (one of them is Lucas Giolito). On top of that, Rodón had the lowest swinging strike rate of his career, at 9%. No wonder his 2018 K/9 and K% were the lowest of his career.

Yes, Rodón seems to have a control issue and was not able to force bad swings often, especially on pitches that were not his slider. However, the biggest area Rodón needs to fix, and what should be the easiest for him to fix, is his success against left-handed hitters. Rodón clearly did not have his best stuff last season, and lefties were able to take advantage of that. With 112 left-handed batters faced, Rodón had a 6.79 FIP and a 5.4% K/BB rate. That is terrible even if Rodon was a righty — and heat maps explain everything.

Rodon’s 2018 sinker was not the same as it was in previous years: It did not move as much horizontally or vertically, and it was crushed. That led to a significant decrease in its usage, but when used against lefties, Rodon put his sinker right where batters wanted it:

Carlos Rodón’s sinker against left-handed batters: On the left is ISO/p and on the right is pitch % in each zone.
FanGraphs

Besides the oddity of Rodón throwing more sinkers up in the zone than down, he put his sinker right where left-handed batters were looking last season — so he stopped throwing them as much. However, Rodón did the same thing with his fastball:

Rodón’s fastball against left-handed hitters in 2018: ISO/P is on the left, and pitch% per zone is on the right.
FanGraphs

The overlap is not as stark as his sinker, but it’s clear that Rodón put his fastball in places easy for batters to hit. Just for contrast, here is Rodón’s slider in 2018, which was terrific:

Rodón’s slider against left-handed batters: ISO/p is on the left, and pitch% per zone is on the right.
FanGraphs

That slider is impossible to hit for lefties the majority of the time, unlike Rodón’s fastball and sinker. Now, this all could be a sequencing issue (which would place some of the blame on catchers and the coaching staff). However, Rodón’s sinker was not moving as much, and his fastball’s spin rate rose almost 100 RPMs and was a touch slower compared to 2017. Those factors clearly did not help him.

So what does this mean? Well, this has all been a detailed way of saying that Rodón needs to find a good primary pitch. He has the strikeout pitch in the slider, so he just needs his fastball and sinker to be even just mildly positive, especially against lefties.

How does he do this? He needs to locate his pitches better — for instance, throwing his sinker lower in the zone. A healthy offseason should help, but health aside, if Rodón is to ascend to the role of an ace it needs to come to fruition in 2019.


Lucas Giolito: Rediscover the curve

Let’s be honest here: Giolito was really bad last season, after what was a decent start to his White Sox career in 2017. It took until June 22 last year for his fastball to consistently average 93 mph-plus, and his curveball was terrible throughout the year. Because both of those pitches were so bad, Giolito had to turn to his lesser offerings. He threw a sinker, which was fine, but it’s not an overwhelming pitch. He used a slider, which despite being an above-average offering he threw more than he wanted. When Giolito found his fastball near midseason, he improved, but still not as well as he should have.

Giolito and the White Sox have blamed his shortcomings last season on bad mechanics, and after his first starts this spring training, that does seem probable. In his first spring training start this year, Giolito was throwing his fastball from 93-97 mph, with a new pitching arm action. That is already much harder than what he was throwing before June 22 of last year, which is a great sign because his fastball getting back to form is a key for Giolito. However, Giolito’s biggest improvement needs come from his curveball, his one pitch that was supposed to be elite.

Let’s assume Giolito’s fastball is back, because the velocity certainly has been in spring. If so, that in itself will help Giolito’s curve. However, saying Giolito’s curve was bad last season is an understatement. Among qualified starting pitchers last season, Giolito had the seventh-worst curveball according to Pitch Info’s pitch value/100 pitches metric, at -2.82. According to FanGraphs, Giolito only had a 21.8% outside-the zone swing rate and a 6.3% swinging strike rate on the curve — that is not a good sign for a supposed out pitch. On top of that, batters have swung less and less often at Giolito’s curveball, from his first stint in 2016 all the way down to 32.9% in 2018.

Compare Giolito’s rate to Zack Grienke in 2018, who had the best curveball among starters. Grienke had a 41.7% o-swing rate, 43.9% overall swing rate, and a 15.1% swinging strike rate — numbers that are all a lot better than Giolito’s.

There are reasons for that. According to Baseball Savant, Giolito’s spin-rate on the curve fell 180 RPMs. That placed him at 198th for spin rate among MLB pitchers with at least 500 pitches. If Giolito’s 2017 RPMs on his curveball could be magically imported into 2018, his curve would have rated 121st. While RPMs do not necessarily determine whether a curveball is good or not, such a significant drop is a bad sign. If Giolito can find his curveball, then the league will need to watch out — especially if his fastball is back at mid 90s. If not, well, it is time to abandon the curveball for good, and along with that any hope of Giolito being a top-of-the-rotation starter.


Reynaldo López: Grounder ball

On the surface, Reynaldo Lopez had a great season in 2018, with a 3.91 ERA in 188 23 innings pitched. However, as I detailed back in October, it wasn’t as it appeared.

By this point, everyone should know that Lopez finished on a tear last season; his command improved, though his strikeout numbers were still low for a player with a 70 grade fastball and a supposed 60 grade curveball. Like Giolito, Lopez lost the feel for his curveball. However, the way López differed from Giolito was that López actually was able to find another good pitch (his slider) as his curve disappeared late in the season.

In the months of August and September, when López was much improved in just about every metric, he primarily was a three-pitch pitcher. It was his fastball, changeup, and slider, with his curve sprinkled in when he had the feel for it. However — and this is where López needs to improve in 2019 — he was throwing his fastball 63% of the time. That is not necessarily a bad thing, especially when López’s fastball velocity was in the 86th percentile according to Baseball Savant. But a starting pitcher cannot rely on a fastball as heavily as López does. He did lose his curve, so it would make sense that López relied on his fastball more heavily. But in 2019, his repertoire needs to be more balanced.

The biggest reason why people are not overly excited about López hangs on his strange batted ball data, as Jeff Zimmerman also acknowledged on FanGraphs for fantasy baseball purposes. Among qualified starters, López had the lowest ground ball rate, and the fifth-highest fly ball rate.

While that alone does not indicate if a pitcher is bad or good, but in the home run park that is Guaranteed Rate, one would assume López had one of the higher home run rates. However, López’s home run rate was in the middle of the pack, because his HR/FB rate was ninth-lowest among qualified starters. López, to put it mildly, got a little lucky, especially since Lopez’s infield fly rate was the fourth highest in baseball.

Launch angle heat maps should not as red as this:

López’s launch angle, by zone
Baseball Savant

Here is where a pitching arsenal comes to play; Lopez’s curve, which he should abandon, had a 53.8% fly ball rate to just a 15.4% ground ball percentage. This is downright terrible, but at least he only used that pitch 5.5% last season, according to Pitch Info. López’s fastball, which was used 60.5% of the time, had a fly ball rate at 43.9% and a ground ball rate at 30.7%. Meanwhile, his change had a 42.3% ground ball and 29.8% fly ball rate. The slider, his best pitch in 2018, saw a 36.7% fly ball rate along with a 32.2% ground ball. Almost half (45.5%) of those fly balls against Lopez’s slider were infield flies. However, the slider and changeup only accounted for 32.2% of pitches.

So to increase ground balls, López needs to drop the curve and reduce his fastball use by around 10%. Theoretically, he’ll see a bump in his K-rate as well.


As you can see, the White Sox’s core three pitchers are not perfect, and have things to work on. The point of this “next step” piece is to identify something everyone can actually watch out for with each pitcher, beyond the vague and typical, “Oh, he just has to put it together” or “just give him a healthy season.”

Those are not constructive suggestions — but hopefully this article is. Let’s hope all these guys get better. Stay tuned for more.