Pablo López Has No. 2 Starter Potential in 2023 — If He Can Make a Slight Change

Last week, what felt like months of Pablo López trade rumors finally came to fruition, as he was sent to Minnesota (along with two prospects) for reigning batting champion Luis Arraez. (For an in-depth breakdown of the trade, check out Ben Clemens’ summary here.) In theory, the trade should help both rosters: the Twins needed pitching depth, and the Marlins needed offensive help. For this piece, I’m going to focus on how López can recover the best version of himself that we saw in 2021 before he missed much of that season’s second half.

López established himself as an above-average starting pitcher in the shortened 2020 season, when he threw 57.1 innings with a 3.61 ERA and 3.09 FIP. The main reason for his success: he bought into the idea of throwing your best pitches more often, throwing his four-seamer and changeup over 60% of the time for the first time in his career. That success carried over into 2021, when he threw 102.2 innings with a 3.07 ERA and 3.29 FIP, followed by a hot start to 2022. But from the middle of June through the rest of the season, he kept tossing up clunkers.

The short story is that hitters stopped whiffing at López’s changeup. He had a slight recovery in the final month, but as you can see in that pitch’s whiff rate and his strikeout rate, that wasn’t him at his best. His repertoire hinges on both righties and lefties swinging at and whiffing on changeups. It’s the key to his success, and it will need to be the focus if he hopes to return to his 2021 form.

So why did hitters swing and miss less at López’s changeup as the season went on, and is it directly related to the pitch itself?

To answer that, it’s worth considering first what a changeup is: a deception. And in order to deceive, you have to make the hitter believe something else is coming. To do that, you must throw your complimentary pitch regularly and in an ideal location. In the case of the changeup, you usually pair it with a four-seamer or sinker; for López, it’s the four-seamer. The success of those pitches goes hand in hand; if one is off, then the performance of the other could be in jeopardy. To go into more detail: if the shape of one changes and no longer tunnels as well with the other, then the combination isn’t as deceptive.

That seems to have been the case with López. Below is a table of his four-seamer/changeup metrics from the last few seasons:

The difference is jarring. López didn’t have pure backspin on his four-seamer to begin with, but a change in shape from the low-80s in Active% (also known as spin efficiency) to 66.2% completely alters a pitch’s shape and, as a result, its effectiveness. Even though his changeup metrics were relatively the same from 2021, the change in the fastball negatively impacted the entire arsenal. If a hitter can distinguish between those two pitches because of shape and/or location, they are less likely to be fooled by either one.

This negative development for López can be traced directly to an injury suffered when he took a liner right off the right wrist on June 10. After that, his performance was sporadic, and more importantly, his release point and pitch location changed:

During his rough patch in July and August, his release point moved down and closer to third base. This slight change perfectly tracks with a loss in active spin. By getting further around the ball, your finger and seam orientation at release are less on top of the ball and more on the side. To get more backspin, you ideally release the ball closer to the top of your fingertips. A change in grip strength that could be the result of a wrist contusion would have a direct impact on these components and cause compensations that take time to realize and adjust to. And while López felt healthy enough to throw 180 innings last year, that doesn’t mean he wasn’t compensating.

When combing through the video, it’s easier to see the change in release. Below are four total clips; the first two are from April, and the two after are from July and August.

There are a few things I want to address. First, López’s altered release point can be traced back in his delivery to a slight change in the use of his glove side. Comparing his throws in the spring to those in the summer, you can see that he’s altered the way he turns his glove over at peak lead arm extension. Early in the year, he only had a slight quarter turn in his glove; in the second half, he progressed into a full turnover.

That subtle difference creates two different reciprocal movements. A reciprocal movement is one that is a direct result of another; if you throw a ball up, it must come down. The same principle works for the body. A change in direction of the glove turn affects the direction of torso rotation, which then affects the angle or position of the throwing arm at release. (The kinetic chain!) That’s an area where he and his coaches can look at when discussing how he can make the proper mechanical adjustments to recover his fastball shape.

It’s important, too, to note how important that recovery will be for López’s tertiary pitches as well. When you lose one of your primaries, hitters can more easily sit on the pitches that aren’t as effective in the arsenal. For López, that pitch was his cutter. After two seasons with a wOBA under .325, the pitch was wrecked in 2022: a .447 wOBA and .321 batting average against. Its downfall can also be traced to his four-seamer, as the pitch went from the mid-50s in spin efficiency to the mid-30s. He may only throw it 10% of the time, but it was still a huge liability. Hopefully whatever mechanical adjustments López makes to recover his four-seamer can filter down to that pitch as well.

Injuries in general can be tough to overcome in the middle of a season. For a pitcher, that difficulty increases with anything related to their arm. A contusion may not be a long-term health concern, but López’s second half shows how something that looks insignificant can lead to detrimental short-term compensations. Luckily for him, this is the type of thing that shouldn’t take any drastic adjustments to fix, and he already has a blueprint for success from his 2020 and ’21 campaigns. With the help of a new coaching staff in 2023, his two-pitch combo should give him and the Twins an above-average starter for the next couple of seasons.