Does Pablo López’s First Month Warrant Serious Concern?

A month into the 2024 season, Pablo López has not pitched as sharply as he did a year ago. Through his first six starts, Lopez has complied a 4.83 ERA, 3.97 FIP, 89 ERA+, and six home runs allowed in 31 ⅔ innings of work.

On the other hand, he’s also kept opponents to a .220 batting average, struck out 29.4% of the batters he's faced, and only walked seven batters in total, compiling a 5.6% walk rate. Not all his stats show cause for concern on paper, but his last two starts (against the weakling White Sox and Angels) have not been pretty. 

Lopez exited his start against the Sox early, pitching only through the fourth inning--wherein he imploded, giving up two hits (including a home run to Eloy Jiménez), two walks, and a throwing error trying to pick off Danny Mendick. Until that fateful frame, López had been cruising through the game, but that bad inning doubled his pitch count from 38 to 76, and he was pulled to protect his arm from further stress.

Things played out similarly Sunday against the Angels. He was perfect through the first four innings of the game. Then, come the fifth, everything changed.

The Angels put together a two-out rally with a walk and four hits, including back-to-back home runs by Luis Rengifo and Nolan Schanuel, which brought López’s pitch total from 60 to 87.

There are stretches in games where López demonstrates his capacity for dominance, Sunday being a perfect example, but it’s only taken one bad inning to have him exit his starts early. So, what is López doing that is allowing hitters to make their at-bats more successful against him at key junctures?

There might be two indicators for Lopez’s regressions early this season: the pitches in his arsenal hitters are having more success against, and how much harder they are hitting those pitches. 

When batters have put the ball in play against López this year, they've posted a hard-hit rate of 47.6%. However, that rate has declined over each game; only five balls in play Sunday were hit over 95 MPH. This was down from seven against the White Sox on Apr. 23 and six against the Orioles on Apr. 17.

Encouraging though the trend arrow might be, however, López's overall rate of hard contact allowed is up significantly from 2023. To explain that, we need to look at the specific pitches on which hitters have done damage against him.

Of the five pitches in López’s arsenal, hitters have batting averages of over .300 on three of them: his sweeper (.304), curveball (.333), and sinker (.429). In the previous two seasons, López has had only one pitch against which hitters have had a batting average over .300. That was his cutter in 2022, which had a .321 opponent average; he’s stopped throwing that offering since joining the Twins.

López’s sweeper has been his second-most used pitch this year, behind his fastball. He’s thrown it 107 times. He's still getting a good whiff rate on it, at 36%, but batters are still 7-for-23 with one home run. Fortunately, López’s only home run allowed on the pitch came on Opening Day, when Maikel García tagged one in the bottom of the first.

His curveball, which López has thrown 51 times, is showing similar results, as hitters have a 42.1% whiff rate when they swing. But in the 12 at-bats ending on a curve, they have gotten hits four times. The one home run he surrendered on this pitch was last Tuesday, against Jiménez. During Sunday’s start, López threw his curve seven times, getting one of his eight strikeouts on the pitch, but the other six times, his curveball neither landed in the strike zone nor got the whiff for which he was hoping.

Finally, there’s López’s sinker, which has had the most alarming results against it. It’s the pitch he’s thrown the fewest times (27) of any this season, but when it has been thrown, hitters are licking their chops and making nothing but solid contact on it. It’s the only pitch on which he has had zero swings and misses, and even with limited use, batters are still 3-for-7 against it. 

These three pitches have alarming numbers next to them. His breaking stuff (the sweeper and curve) is showing signs of improvement as the season has progressed, but whatever is going on with López’s sinker, it's steering some of his struggles early this season. Despite his limited use of the pitch, it’s lining up directly into hitters' wheelhouse, and no matter what López tries, it has yet to get past any hitter's bat.

If López works on the struggles he has had with these pitches between starts, the results with his hard-hit rate may change in his favor. The only season wherein his hard-hit rate was remotely close to 40% was in 2019, when it was at 36.9%. He's good at inducing weak contact. He just needs to get back in touch with that skill.

Despite the flaws in these six starts, there are still signs that the best is yet to come for López in 2024. His strikeout-to-walk ratio is higher through six starts this season than it was last year; it currently sits at 5.29, compared to 5.11 through six in 2023. Additionally, his WHIP sits at 1.04, which is tied with teammate Joe Ryan for 15th-best in all of baseball. 

Do these early season struggles with three of López’s five pitches and how frequently batters are making hard contact off them warrant real concern from fans? No. López has had slow starts to his seasons before, and has bounced back with his best starts in the summer. These are things for Twins fans to keep an eye on when watching him on the mound, and if his track record holds up, they’ll see better results all-around.