Two months of the season. More than a third of the total regular-season baseball we’ll get this year. That’s enough games for a pitcher to have done something one way, then changed it up and given us a large enough sample to see that something is truly different now.

So, which pitchers have made changes over the last month, and given us a second act that might preview a grand finale?

Here are the starting pitchers who have changed their Stuff+ the most over the last 30 days, when compared to April numbers.

It’s nice when the process stats line up with a complete change in results, as they have with Roki Sasaki. His move to a harder splitter in favor of the forkball has given him more in-zone options and pushed his strikeout minus walk rate from terrible to elite in a four-start stretch. Finding another tick on the fastball has to be part of the story, but for the entire perspective, read Fabian Ardaya’s excellent piece on the subject.

Some of these pitchers, like Tomoyuki Sugano and Michael McGreevy (not in the table, but he had a +3 Stuff+ jump), didn’t have great stuff to begin with. They survive by throwing wide pitch mixes with decent command. But a few of these names are intriguing enough to highlight on their own.

Aaron Nola, RHP, Philadelphia Phillies

Though some of the stuff numbers have changed, Nola’s process stats remain remarkably similar to those he was putting up in the first month. He had a 15.7 percent strikeout minus walk rate in the first month, and it was 15.2 percent in the second month. His SIERA was high 3s both months. And his ERA in any month has been terrible.

Can Phillies fans and wannabe Nola buy-lowers take heart in the improving Stuff+ numbers? Maybe not.

The good news is that, before his last start, he’d been steadily improving his velocity. From the doldrums of the 91 mphs early in the season, he’d pushed his fastball up to the high 92s and even had a start at 93.4 against the Padres. With the average right-handed starter averaging close 95 on the fastball, that’s still not great, but it’s better. His curveball added a little drop, his fastball a little ride and everything was a little crisper in May than it was in April.

The problem right now seems to be lefties, though. He’s allowing a .311/.396/.515 line against them that is both untenable and part of a five-year trend in the wrong direction. And when you look at his Stuff+ versus lefties, set against the results on those pitches, the problem becomes pretty clear.

Aaron Nola versus lefties

PitchPercentageStuff+SLGxSLG

Curve

34%

127

0.381

0.284

Four-Seamer

29%

100

0.974

0.762

Changeup

18%

63

0.091

0.321

Sinker

13%

96

0.389

0.493

Cutter

7%

92

0.455

0.277

He just doesn’t have a hard pitch that’s profiling all that well against lefties. The only one that theoretically should work (the four-seamer) gets pummeled. Over the course of this season, he’s thrown fewer four-seamers to lefties and more cutters. If you want to take solace in anything, maybe it’s his increase in cutter usage — up to almost even with his sinker, four-seamer and cutter usage in his last game.

But in the face of this overall problem versus lefties, it’s hard to recommend him strongly as a buy-low in fantasy.

Emmet Sheehan, RHP, Los Angeles Dodgers

It’s not quite Mr. Toad’s Wild Ride, but the velocity chart for Sheehan this year has been a roller-coaster.

There are more erratic charts, maybe. Judged by the spread in start-to-start velocities, Sheehan ranks just outside the top 20, around Freddy Peralta and Gavin Williams, and nowhere near Chris Sale and Jacob Misiorowski, as well as some injury-plagued pitchers like Kodai Senga and Cole Ragans. But Sheehan has done better in his higher velocity starts and so this is a relevant angle from which to look at him, especially since his Stuff+ improvement has mostly come from adding velocity to his four-seamer.

But there’s more going on. He’s added more cut to his slider and leaned into its usage. He seems to be de-emphasizing the changeup. And lefties slug .496 against him. These things seem related, since the changeup should be a big weapon for him versus lefties.

Overall, though, the trends are positive. This is a young pitcher who seems to be settling in on the velocity side and has some tinkering to do with his pitch mix against lefties. He gets the White Sox, Orioles and Padres over his next three starts and seems like a decent start in all of those matchups.

Noah Cameron, LHP, Kansas City Royals

There might be some real pitch changes happening for Cameron. His curveball jumped nine points of Stuff+ by adding a tick of velocity and a little horizontal break. His slider jumped 10 points by adding that same tick of velocity, proving yet again that velocity is as important for secondaries as it is for fastballs. His changeup did the opposite, losing a bit of velocity from start to start since May 10, and since it’s a lower-movement “straight” changeup, that’s been good for its model numbers.

After some early ups and downs, Cameron’s four-seam velocity has held steady around 93, too, which is a tiny bit better than last year. That number is a limit on his upside, but he’s now showing three secondaries that are plus pitches, which was the same formula that drove his rookie success.

A lefty with a good changeup, good command and multiple secondaries he can use to play off each other appears to make him a good bet to put up numbers on the best side of his projections. This high-3s ERA with a good WHIP seems sustainable despite some models calling for a high-4s ERA.

Jack Flaherty, RHP, Detroit Tigers

Over at least 10 starts, Flaherty has the third-wildest velocity swings in baseball from start to start. The fact that three of his five best velocities have come in the last three starts bears a lot of weight here. Rob Arthur once found that the hot hand for pitchers was real, and basically related to fastball velocity, so there’s a lot here.

Flaherty has also upped his slider velocity recently, and that’s helped the whiff percentage climb from below 20 percent early in the season to over 33 percent since the beginning of May. That’s pushed his strikeout minus walk rate from terrible in April (4.9 percent) to great over the last 30 days (21.4 percent; around 14 percent is average). This is all good news, and the schedule abides to varying degrees, with the Guardians, White Sox and Astros coming up.

But, for a pitcher who once famously ranted about fastball velocity, this all seems built on a pretty shaky foundation, given those wildly moving radar gun readings.

Sean Burke, RHP, Chicago White Sox

Speaking of solid foundations, Burke’s fastball is his cornerstone. It’s been around 94 with great ride all year and has provided him with an identity.

The work has been improving the pitches around that piece. Specifically, the slider. He’s added horizontal and vertical break to the pitch, and it’s about the best it’s been. Now more than half of his sliders are over 85 mph — traditionally a marker for “good slider velocity” — with above-average drop. Last year, only 38 percent of his sliders met that criteria. His whiff rate on the pitch is in its best six-week stretch of his career, and his average slider looks a lot more like this now.

That’ll do.

While the hope for Shane Smith was similar and yet not realized, there’s a key difference between the two. They both have great fastballs and needed to work on their secondaries, but Burke’s command grades, from the time he was a prospect all the way up through the major leagues, have always been better than Smith’s. That probably foreshadowed Burke’s ability to improve the shape of his secondaries.

He may still have some weakness against lefties when he needs to go to the secondaries, but other than perhaps his next start against the Dodgers, Burke looks more and more like an every-start guy in fantasy baseball and a big (if slow-moving) win for the White Sox coaching and development staff.

Justin Wrobleski, LHP, Los Angeles Dodgers

Two things stand out at first when you look at Wrobleski through the lens of Stuff+. For one, his slider is two ticks harder than it was at the beginning of the season. And two, his changeup is dropping three inches more than it did to start the season, thanks to a new split-change grip that he’s refined. Of course, the first is more important as he’s throwing the slider two-fifths of the time and the changeup a handful of times a game. But they’ve both contributed to his run of success.

Wrobleski had a really bad strikeout minus walk rate earlier in the year (4.9 percent) and was in the top 25 among qualified pitchers in the last 30 days in that stat. It seems like a little more than a slight improvement in his slider has driven this.

Could it be a combination of those pitch improvements and a change in locations? Here are his fastball locations to righties in April and May, courtesy of Baseball Savant.

Now he’s dotting the inside corner to righties with the fastball, hitting the back-foot corner with the slider and increasingly playing the changeup off the slider if the hitter starts targeting the breaker. All of this is set up by better fastball velocity, better slider velocity and better shape on the changeup, but it all works together.

Sometimes, the predictive stats miss that a young player is changing in front of our eyes. Yes, Wrobleski had bad strikeout rates before. Now he doesn’t, and the underlying stuff supports the breakout. Last month’s 22 percent strikeout rate seems like a true talent number, and he’s always had the command to put up great walk rates. The Dodgers are going to need him all year, too. He’ll move up in next week’s rankings despite some mediocre ERA projections.