Here’s a look at Reynaldo López’s shorter arm swing

CHICAGO, IL - SEPTEMBER 17: Chicago White Sox pitcher Reynaldo Lopez (40) throws a pitch during the MLB baseball game between the Minnesota Twins and the Chicago White Sox on September 17, 2020 at Guaranteed Rate Field, Chicago, IL. (Photo by Kiyoshi Mio/Icon Sportswire)

Reynaldo López will make his second appearance of the spring when he faces the Reds in the first night game on the White Sox’s Cactus League calendar. Alas, Cincinnati isn’t offering a video broadcast or webcast of this one, so López’s new look will remain elusive, at least against live competition.

The White Sox did try to step in and fill the gap with a produced video of López and Ethan Katz, and it’s cool for a couple reasons. The first is the visual component, which gives you some idea of what his reworked mechanics look like.

It might have been a while since you watched López closely, because White Sox fans probably didn’t want to see him at all. The unconventional angles of spring training make it difficult to stack up with readily available game video, but I found a James Fegan spring training video from 2019 that had a similar range and vantage point. Here they are side by side, with López’s new version on the left.

James shot his in slo-mo, so he gets points for precision. The difference in frame rate makes it hard to match up the exact lowest point of López’s new arm swing, but here’s my best attempt at freezing it:

It may be off by a millimeter or three, but López’s new arm path is indeed different, and similar to what Lucas Giolito and so many other pitchers have done. This recent Twitter thread by Travis Sawchik goes into details about the movement’s movement, and other examples besides the in-house one that might set the bar a little too high. López doesn’t need to be a Cy Young contender to help the White Sox this year. A decent No. 4 starter would be more than plenty.

Besides the mechanical alteration, you’ll also want to listen to the audio. In particular, just before the two-minute mark is a conversation between López, Katz and Jonathan Lucroy, who is catching the session.

Lucroy [to López]: … curveball? What do you like throwing better with two strikes?

Katz [to Lucroy]: So, the curveball. He threw it with the Nationals. That was his best secondary pitch. He came here, he dropped it. So the curveball is coming back into the picture this year. It’s a brand new– it’s not brand new, but it’s new, it’s been a while. So it’s back in the picture and getting him to re-acclimate that is kinda new for him.

Some might read that as a shot at Don Cooper, but a simple recitation of López’s curveball usage from FanGraphs says the same thing:

  • 2016: 25.3% (with Washington)
  • 2017: 12.9% (with Chicago)
  • 2018: 5.6%
  • 2019: 6.6%
  • 2020: n/a

The Cooper administration favored the slider over the curveball for pitchers because it’s a more reliable strike-getting pitch. It transformed Gavin Floyd among others, but it’s had diminishing returns, especially since a good curveball has proved to be an effective complement to the high fastball that’s so fashionable these days. López’s return to the curve makes sense, as long as the new arm path means he still has the feel for it.

The video only features positive reinforcement because it’s a White Sox-produced joint, and other standard spring training caveats apply as well. Regardless, unlike López’s previous attempts to address his struggles that emphasized focus and mentality, the detectable changes to watch and track are a welcome departure.

* * * * * * * * *

The above analysis on López didn’t get into the weeds on tunneling, and Giolito avoided the same rabbit hole when explaining how his changeup worked in a Zoom call with Lost Boyz, a South Shore organization that works with at-risk youths. Giolito does an admirable job of simplifying the concepts to kids over remote video, so much so that it’s probably useful for adults, too.

(Photo by Kiyoshi Mio/Icon Sportswire)

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I think we might end up being pleasantly surprised with the progress that Lopez, Cease and others make this year working with Katz. It just seemed Coop had a philosophy on how to pitch, and it didn’t matter who the pitcher was, they were going to pitch that way. Having Katz in charge will probably make a huge difference to many of these guys who struggled pitching Coop’s way. Katz knowing that Lopez 2nd best pitch in 2016 was his curve is very impressive. It’s obvious he has done his homework on each pitcher and their strengths. Now if that can translate to the mound during the regular season, we’ll have a very formidable staff.

On a related note, any news on Rodon? I would assume he has the edge on Lopez for the 5th spot, since Rey has an option left. When will he see some real live game action?


I really enjoy the point in the Katz video when he brings up the old regime making Lopez ditch his curve and is clearly on the verge of shit talking Coop, but then remembers he’s mic’d up.


really excited about katz’s impact on this pitching staff. coop had some great successes back in the day, but his clear insecurities around non-insiders having ideas have been holding the sox back for a while. he was all too eager to condescend when given the opportunity. he begrudgingly accepted the presence of data and technology, so i wonder how much he used/embraced that stuff in his work. glad we’ve got one dinosaur out of the org.


Great video with Giolito. I like that guy.

LuBob DuRob

It’s quite the battle between Timmy and Gio for most endearing and genuine Sox. The whole team is so damn likable.


It’s also kinda hard to see, but his back (throwing) shoulder is staying closed. Not only is it not dipping with the arm action, but it’s not twisting backwards as much. It also looks like he’s not going past center with his leg kick. The “go back to come forward,” is minimized. I hope it all helps.

Goof stuff, Jim!

Last edited 2 years ago by lastof12

I was going to say something along those lines but I only have those side by side pictures to go off. I can’t actually tell if anything other than his arm angle has changed because of shadows and the angle the picture was taken from.


Who has the higher ceiling as a 5th starter in 2021, Lopez or Rodon? I know that I’ve been pretty harsh on Lopez in the past, but I think at this point I would seriously lean him in a head-to-head. The arm talent is there so that a tweak to his mechanics or pitch selection could unlock a pretty good pitcher.

Also, I’m biased because in my head Carlos Rodon and Brad Hand are basically the same pitcher. Their deliveries are almost identical with Hand having a slightly smaller leg kick and a bit more exaggerated follow through. Rodon has a much better fastball (more velo, more vertical movement) and throws a slightly harder slider with less horizontal movement. He could really just be a version of Hand if he ever really embraced a reliever role. Rodon seems to still think he’s a starter, but the reporting from White Sox insiders when he was signed made it seem like the team had him targeted more in a relief role. If they can get “Brad Hand Lite” for $3M instead of $10.5M for the name brand, I like the signing a whole lot more.

Also Lost Boyz is an awesome organization. I’d encourage anyone to read up on it and donate if you are able to.


It’s always been Lopez, which is what is so annoying about him.


Jeez, this is a bad look for Coop. The biggest thing I takeaway is from Roke1960’s comment about not adapting to an individual’s strength or comfort level when it came to pitch selection. It was always fastball-slider-cutter. And while that worked wonders for some (Quintana is the one the most comes to mind) it seems to have been a misguided strategy for Lopez and Cease, who had legitimate major league curve balls when entering the organization.

I was always a Don Cooper fan, especially in the 2000s when he made so many pitchers better. But seems like he became set in his ways and didn’t adapt to new technologies or his approach with different skill sets to maximize the talent he had. Perhaps he can find work with the Chicago Bears offensive staff.


Another point that was in a previous article, but I don’t think was mentioned here: Katz also said Lopez was tipping his pitches. Now, I don’t know the context of that (just in his short time last year or for a while?), but combine that recognition/elimination with real mechanical improvements, and I’m starting to get optimistic about Lopez, who I had completely written off.


The talent is there and always has been. We’ll need to see if the changes actually help and if they stick. I feel like Katz is going to have one or two success stories this year that make the staff formidable.

More and more I’m thinking 99 wins.


It really comes down to injuries, especially to the top 3 starters and the offense. The bullpen is so deep, they can get by with a few injuries/underperfromers. But if Giolito, Keuchel or Lynn go down for any length of time, or 1 or 2 of TA, Yoan, Eloy, Abreu, Robert, Grandal, then we could be in trouble. If those 9 guys stay healthy, 100 wins is certainly possible.


The real step is going to be about the young players showing tangible improvement. Madrigal cleaning up the defense and being more comfortable with his shoulder, Robert adjusting to the late season adjustments teams made against him in the box, Vaughn looking at least hitterish in the first half, Kopech and Crochet locking down the BP.

If those players showcase the improvements we expect, 101 wins is plausible.


Do I hear a 102? 101 going once…


Fine, name that tune. Wait, I think I did this wrong.


So Tony LaRussa, Manager of the Year?

Joliet Orange Sox

I think LaRussa would have a real shot at manager of the year if the Sox do win 125 games.

Last edited 2 years ago by Joliet Orange Sox
  1. TLR having a shot? uhoh. . .sorry, bad joke
  2. 100+ wins, is that the level everyone has to pledge fealty?
Eagle Bones

So I seem to recall both Lopez and Giolito making comments when they first came over to Chicago and got called up about having trouble throwing their curveballs because of the MLB ball and something with the seams making it hard to get a good grip. Blake Snell made comments just the other week about the tweaks that MLB made with the ball this offseason making it easier to grip the seams for his curve. I wonder if there is some kind of connection here?


But then you have Kershaw saying it feels the same to him.

Eagle Bones

Yeah probably a case by case basis and depends on your grip. I also wonder if this is what necessitated the move away from the curve for both (i.e. it was more they couldn’t get comfortable throwing the curve and just gave up on it rather than Coop specifically moving them away from it to the slider just because he likes sliders better).

karkovice squad

They data backs up that they had significantly less effective curves after they debuted with the Sox.

We don’t really know whether it was the ball, something the coaching staff did, or just something the coaching staff didn’t know how to fix or preferred solving with a slider.

Trooper Galactus

Man, if Cease and Lopez both have a big turnaround, it’s gonna be a pretty bad indictment of Don Cooper’s last few years in the organization. Given how heavily the team was relying on developing young starting pitching to carry them to contention, Cooper’s stagnation in this regard was becoming more and more egregious.

Joliet Orange Sox

López gave up 5 ER in 3 IP tonight against the Reds. I’m not giving up on him because he’s young with a good arm. However, it occurs to me that some of the talk in these comments about his progress proving Katz is a huge upgrade over Cooper may be a bit premature.


López is 27 and has thrown close to 500 innings in the show. The odds that Katz actually turns him around have to be extremely small.

Eagle Bones

I believe I saw reports that his velocity was still down, similar to last year. If so, that’s not good.


Listening to Coop speak on the Score yesterday I think letting him go was the right call, even if I was generally a fan. Angry old man vibes for sure. Coop and Katz have different skillsets that could both be beneficial to a pitcher, but with all the young pitching the Sox have right now I think a guy like Katz is the better fit.