Carlos Rodón didn't have the time to make his initial pro ball adjustments in the Minor Leagues. Less than a year after being drafted third overall by the Chicago White Sox in the 2014 MLB Draft, he was summoned to the Majors, having thrown all of 34 2/3 innings over eight Minor League starts.
So it's not a surprise to see Rodon find things along the way, like that moving toward the third-base side of the rubber halfway through his rookie year would help with his fleeting fastball command. That's the sort of early-career adjustment that might typically happen out of the public eye, under the watch of a Double-A manager. Rodon is not going to have the typical career. We'll see nearly every adjustment he makes -- and we're seeing one right now.
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In the first Major League start of Rodon's career, he threw 70 fastballs, 36 sliders and two changeups. The fastball touches 97, and it's not every day you see that from the left side by a starter, so of course he'd lean heavily on the fastball. The slider has long drawn rave reviews, too -- Baseball America called it "one of the best sliders college baseball has seen in years, a 70-grade pitch" in their 2015 preseason scouting report of Rodon -- so of course he'd often go to the slider. But then there's that changeup, which BA said may flash plus, but without consistency. It's what you hear so often from young pitchers as they look to differentiate themselves as a true starter among a pack of potential future relievers.
As expected from a pitcher with an inconsistent changeup, Rodon has largely struggled against opposite-handed hitting. Oh, the fastball and slider have done a number on the same-handed bats. Rodon has struck out more than a quarter of the lefties he's faced with a league-average walk rate, allowing a .255 Weighted On-Base Average while running a 2.57 Fielding Independent Pitching, but the numbers against righties have evened things out -- 4.44 FIP and .347 wOBA allowed -- and Rodon has faced more than three times as many righties.
But lately, there's been a development. First being, Rodon has been among baseball's best pitchers in the month of August, running a 1.47 ERA and a 2.66 FIP over five starts. And while it's easy to overlook a five-start stretch of dominance as being just five starts, it becomes harder to ignore those five starts when they coincide with this:

In this month, during which he's dominated, Rodon has thrown 91 changeups. In the four months prior, he threw a combined total of 115. The uptick began in Rodon's first start following the All-Star break. Percentage rates are more telling.
Rodon changeup usage
First half: 6.0 percent
Second half: 17.3 percent
The changeup rate has tripled. Righties have seen it a quarter of the time on the first pitch. Rodon has used it while behind, he's used it while ahead, and he's used it as a strikeout pitch. The usage figures alone indicate that he has developed a greater feel for the offering. Rodon's numbers during the usage spike support his decision. But we can dive deeper to figure out with what kind of a change he is working, and whether it might be here to stay.
When FanGraphs' Jeff Sullivan wrote up Rodon's slider back in February, he used the pitch's velocity and movement readings to find an individual pitch comp, and he found that, by the end of the year, the slider Rodon was throwing was almost identical in terms of velocity and movement to the slider thrown by Clayton Kershaw. Doing the same with the changeup, while folding in spin rate, we get Alex Wood, Gio Gonzalez and Matt Moore as our top three comps. Quality Major Leaguers with quality changeups. Only a little further down, we get Cole Hamels.
Rodon's changeup gets 10 mph of separation from his fastball, an amount that typically makes for strong whiff rates. Rodon's whiff rate on the change has been soundly above average. It's shown both more horizontal and vertical movement than the average change, according to PITCHf/x. And when Rodon is throwing it, he's doing a better job of keeping it down in the zone, relative to the first half.
Let's see it in action. It's always instructive to see it in action. This comes against Miguel Sanó, from Rodon's first start following the All-Star break -- the first start in which a greater emphasis on the changeup is noticeable. But before we see the changeup, let's see a first-pitch fastball.
Gif: Carlos Rodon Ball
It's a good fastball, a well-located fastball, but it misses just inside for ball one. Now, behind in the count against a dangerous opposite-handed hitter, Rodon needs a pitch he can trust to get back in the count while limiting damage. Sano wants the fastball. A slider breaking toward Sano's barrel can be a frightening proposition. So Rodon goes to the pitch he didn't have until recently:
Gif: Carlos Rodon Changeup
It's a pretty changeup, with noticeable late arm-side fade away from Sano's barrel. The rest of the at-bat goes: 1-1 changeup (swinging strike), 1-2 slider (foul), 1-2 changeup (ball), 2-2 fastball (foul), 2-2 changeup (swinging strike).
The last thing I wanted to do to measure the quality of the offering was to gain a sense of Rodon's arm speed with the pitch. Any quality Major League changeup is thrown with the same arm speed as the fastball, so as to gain the full effect of the changeup looking like the fastball out of the hand, and to avoid the potential tipping of the pitch. Take a look at his arm speed, and if you can spot a noticeable difference, you're seeing more than me.
What we have here appears to be a Major League pitch. We see good velocity separation with strong arm speed. We see plus tilt and fade. We find some encouraging comps. We notice an uptick in usage, indicating an improved feel, an assertion which the observed command of the pitch backs up. Command can come and go, and of course sustained command is the key, but Rodon has been demonstrating it lately (though it's still certainly not as refined as it could be) and the quality of the pitch on its own appears promising, potentially leaving some room for error as far as the command is concerned. It's the plus changeup Rodon flashed in the scouting reports, only the flashes are occurring more consistently.
Rodon's changeup is looking like a quality Major League pitch. And that sure goes a long way toward a quality Major League pitcher.
A version of this article first appeared at FanGraphs.com. This story was not subject to the approval of Major League Baseball or its clubs.