Which Jose Urena curveball are we talking about?

The Miami Marlins have to be happy thus far with the returning performance of Jose Urena, who has pitched well since coming back in mid-July to the rotation thanks to a series of starter injuries. Urena has filled the role admirably, throwing 53 ¹⁄₃ innings pitched and posting a solid 3.88 ERA and 4.00 FIP thus far. Most recently, he struck out four batters and almost went the distance for a complete-game shutout of the Los Angeles Dodgers before settling for 8 ²⁄₃ innings of great baseball en route to an eventual shutout victory. A complete game would have ended the longest drought of complete games in Major League Baseball, as no other team has gone as long as Miami without a starter going all nine (a record 410 games and counting).

After the game, there was some talk about Urena’s success on MLB.com, and it was an intriguing read. Of note, there was something written about a specific pitch that Urena was using.

One reason Urena was so effective was his improved curveball, which gave the Dodgers something else to focus on as well as his 95-plus-mph fastball, changeup and slider.

"We hadn't used it that much with lefties," Urena said. "A lot of lefties are looking for a changeup. We were combining them, changeup on the corner and the curveball, too."

It was noted that Urena was using his curveball to good success and that was the reason why he was more effective. Interestingly, we just discussed Urena’s upside and made no mention of his curveball at the time. Looking at his timespan as a starter since July 2016, it looks as though Urena has thrown a curveball, at least one recognized by Brooks Baseball, 25 times. It seems hardly likely that a curveball thrown just three percent of the time would be the key to confusing hitters in this most recent run of success.

But Urena was not saying that he had been using it since July. It looks as though he is stating he is trying it against lefties more recently. Does that bear out in the data? It does not appear to be the case either; since the start of September, Urena has had three starts and has thrown three pitches that were classified by Brooks Baseball as curves. However, the raw data from MLB Gameday has him throwing a curve eight percent of the time this month, about the same amount as he is throwing his slider.

To confuse the two would make sense. Take a look at their movement and classifications by Brooks Baseball since July of this year.

You can see that these two pitches are almost two sides of a very similar coin. The curveball breaks downward more, while the slider supposedly has a flatter feel. Neither breaks all that hard away from right-handers. Their breaks are pretty similar, as are their velocities. This is not a common occurrence, as most player’s curveballs are more than two mph slower than their slider. It is almost as if these two pitches evolved from the same pitch, likely initially a slider, and diverged at some point in development.

The quote does talk about Urena working it in more against lefties, and that does seem to be the case. Almost five percent of his pitches against lefties since July have been curves, while only about 10 percent of them have been sliders. This is slightly changed from their overall rates of three and 13 percent respectively. In total, he has thrown 22 of his 25 curves since July against only lefties. It does seem like Urena favors the curve-like offering more against lefties, but notably he only prefers the pitch as a “get-me-over” called strike rather than a whiff weapon. He threw the pitch most often on the first pitch and on even counts, going to it nine percent of the time in both scenarios. In contrast, he turned to the curve just two percent of the time with two strikes.

You can see the problem with the curve in terms of getting whiffs. In the tiny sample of 25 pitches, only 20 percent of them were swung at, and batters made contact on all of them. In general, it has done better before, with a 39 percent swing rate in the past and a 21 percent whiff rate. Like one would expect, Urena gets more called strikes with the pitch than swings, as he throws the pitch more around the strike zone. He has a 1.9 balls to called strike ratio on the pitch, which is closer to a ratio on a bad fastball than an out pitch, but relatively common for curve throwers.

It does not appear that the curve is keying the resurgence of Urena. He just is not throwing it often enough against lefties to make a difference. What he is doing is going to the slider a little more often as well, and that goes back to the point about confusing the two pitches. Last year, Urena went to the slider just four percent of the time against lefties, versus 10 percent this season. It is getting plenty of whiffs, garnering a 32 percent whiff rate since his July return. It seems he too is developing the mantra of throwing sliders at the feet of left-handers, and that may be his additional weapon with his changeup on the opposite side. With all of this, however, it still has not helped, as he has thrown terribly against lefties, posting an ugly 5.01 FIP. If he wants to remain a starter, he still needs to find craftier ways to minimize his platoon problem.