A month ago, Cody Christie wrote a great article around Jhoan Duran’s decreased velocity, and how that has impacted his pitch mix changes. A couple findings from that article were that:

1. His velocity is down roughly 1.2 MPH on every pitch compared to 2023, through mid-May.
2. He’s been throwing his heater much less, and relying on his off-speed offerings more. At that time, he had decreased his fastball usage from 45% last year, to 34.3% this year through mid-May.

Well, this trend has continued, and his results have gotten worse. Duran has not found his missing velo, and his fastball usage reduction has become even more extreme. Here are his past three games:

• Last night, when pitching in back to back games, he only threw two 4-seam fastballs out of 10 pitches, and barely broke 100, at 100.1 and 100.4.
• The night before, Duran had a bit more gas, breaking 100 on all four fastballs (out of 15 pitches), with fastballs at 101.8, 101.1, 101.1, and 100.2.
• On Sunday, Duran threw fastballs four times, and failed to break 100 on two of them. What this tells us is that recently, his fastball usage is down to around 25%, and his velocity is down even more.

While Cody’s article focused on velo and pitch mix, this article is going to take a deep dive into his pitch effectiveness and some pitch characteristics. To start that discussion, let’s take a look at his xwOBA throughout the season.

When Cody wrote his article, Duran’s xwOBA was sitting at .237, on a league average of just over .300. Today, his xwOBA is sitting at .281. That’s still better than league average, but it’s not world-beating any longer. But why?

Looking at Statcast and Baseball Savant data, so far this season, Duran has had only one effective pitch - his splinker. Throughout ’24, that is still a consistently great pitch for him. However, his fastball and his curve have both been much worse than typical for him, and rank poorly overall.

So, what has changed since last season, aside from his velocity dip? Last year, each of his offerings were good, and his splinker was GREAT. Digging deeper, we can see that this year, his overall chase rate is down almost 4%, and his whiff rate is down 4.6%. His strikeout rate is 2.3% less than last year (but his walk rate is down slightly as well. Batters are hitting him less hard, but they are also elevating the ball more, as evidenced by his ground ball rate dropping 5.5%. Overall, his xBA is up almost 30 points year over year.

But why? Let’s look at his fastball and curveball separately. We will start either his fastball.,

Fastball

This year, Duran'is fastball has lost some vertical drop compared to the average fastball, so it’s likely that hitters are perceiving the pitch as more crushable.

Location has also been a factor for his fastball success. See his heat map for last year - a lot of pitches up, leading to a lot of swing and miss.

This year however, his fastball is generally going much lower, and it’s resulting in a roughly .800 xOPS - not what you want to see out of one of the best pitchers in baseball.

Curveball

We can see that his curveball used to be a putaway pitch, but now isn’t.

Here, we can see that his spin rate is down on his curveball, losing about 100 RPM since last year. His splinker and fastball have both lost a little spin as well, but its not drastic. We can also see that his extension is down slightly, so that likely accounts for some perceived velocity loss in addition to the actual loss.

His pitch location also may be impacting his results. See these comparisons:

Here we can see that last year, Duran threw a lot of curveballs that missed just low, leading to more whiffs. This year, his curves are tending to miss VERY low, which helps to explain his decrease in effectiveness. If a batter know’s it’s a ball, they won’t swing, and there’s a pretty good chance that with some of these locations, they just know.

Overall, the story this all tells is that Duran is a great pitcher who is struggling with some mechanics, and locating his pitches where they are most effective. Even when throwing a little slower, he still ranks near the 100% percentile in velocity. His stuff will play. Here’s to hoping that he and the coaching staff can get the mechanics and the command back on track.

What do you think? Are better days ahead for the flamethrower?