The Phillies wouldn’t have signed Jake Arrieta if they didn’t think they had some chance to win right away. Arrieta would improve that case himself, and his acquisition addressed what had been a thin pitching staff, but even a few months ago, the Phillies were expressing some cautious optimism. Aaron Nola, obviously, is incredibly good. The team was willing to dismiss Jerad Eickhoff’s rough 2017 as a consequence of injuries. And much of the organization was excited about Nick Pivetta. With Nola, Eickhoff, and Pivetta, the Phillies could dream on a rotation that could hold its own, even before Arrieta came along.

Pivetta now has three 2018 starts under his belt, and the last two have been terrific. In fairness, we’re talking about a Marlins lineup that’s not at 100%, and a Reds lineup that’s even further from 100%. The competition has not been stiff. But Pivetta’s struck out 16 of 47 batters, without issuing one single walk. There’s improvement in the results, and even more important than that, there’s improvement in the process. As a rookie in 2017, Pivetta flashed a promising weapon. It would appear he’s now using it with more confidence. It’s time for the National League to get accustomed to seeing Nick Pivetta’s curveball.

Even just eyeballing things, Pivetta was already poised to get better. Over 26 starts last year, Pivetta ran a terrible 139 ERA-, but his FIP- was 109, and his xFIP- was 99. With some regression alone, Pivetta could look like a big-league-caliber starter. But there was plenty of room for him to grow. During the spring, there was a lot of talk about Pivetta more often employing a high fastball. The club actually wanted Pivetta to maybe model himself after Justin Verlander. There are worse pitchers to try to mimic.

Interestingly, Pivetta hasn’t used his fastball differently in the season. His vertical locations haven’t changed. His high-fastball rate hasn’t changed. He’s not throwing high fastballs like Verlander at all, but then, that might make plenty of sense. Our understanding is that, in general, a good high fastball is a high-spin fastball. According to Baseball Savant, Pivetta’s fastball spin rate is only a little above average. Verlander’s spin rate, meanwhile, is elite. Spin rate isn’t everything, and Pivetta isn’t hurting for velocity, but he doesn’t seem to possess the same kind of weapon. Why try to force it?

So, the fastball hasn’t been the pitch worth watching. This isn’t some kind of spring-training plan come true. Instead, the story has probably been Pivetta’s curveball. I present to you his usage rates, over rolling three-game samples.

More and more and more, Pivetta has believed in the pitch. And it seems like it’s a good pitch to emphasize and attempt to polish. Why? Unlike the fastball, the curveball does have elite spin. Last year, among starters, Pivetta’s curve spin ranked in the 91st percentile. This year, it ranks in the 94th percentile. You know how Charlie Morton throws a high-spin curve? Pivetta is right there with him. It’s a good-looking pitch, and Pivetta has improved his ability to move it around.

Maybe you can see that by looking at his pitch locations.

It would appear as if the locations have tightened up. Pivetta has been throwing fewer, shall we say, non-competitive curves. But just as telling, if not more so, there’s the usage.

Nick Pivetta’s Curveballs Situation 2017, Early 2017, Late 2018 All Counts 12% 19% 26% First Pitch 12% 20% 28% Batter Ahead 6% 8% 16% Even 12% 21% 30% Pitcher Ahead 19% 27% 28% Two Strikes 14% 25% 25% SOURCE: Brooks Baseball

You’re seeing a column for last year’s first 13 starts, last year’s last 13 starts, and this year’s first three starts. Even within last season, Pivetta went to the curveball more often. But where do you see the patterns change? Not with Pivetta ahead. Not in two-strike counts. Rather, there are more curveballs now with the count even. There are more curves on the first pitch, and there are more curves with the batter ahead. What’s strongly implied is that Pivetta feels better than ever about his ability to throw a curve for a strike. That makes it a much, much more difficult pitch to dismiss.

For a glance at peak Pivetta, observe a four-pitch sequence from Wednesday, against Jesse Winker. On the first pitch, Pivetta dropped in a curve. Batters don’t like to swing at very many first-pitch curveballs.

Pivetta then came right back to do it again.

At that point, Pivetta was way ahead, and Winker had seen consecutive breaking balls. Pivetta decided to go to that high fastball.

Nothing wrong with the execution — look at the catcher nodding — but Winker fought the pitch off. Winker’s pretty good. On pitch number four, Pivetta stuck with the heat. This time, he went for the corner at the knees.

Perfectly done. Four pitches, four targets hit, three areas pitched to, zero balls thrown. Pivetta didn’t even mess around with a slider. He didn’t have to.

It’s a slider that rounds out his repertoire. A year ago at this point, the slider was probably ahead of the curveball. Now the curveball has taken a step forward, and Pivetta has all but abandoned his changeup. With three pitches to work off, Pivetta doesn’t have an abundance of toys at his disposal, but his fastball has good zip, and he can now throw the curve in two different ways. The first step for any breaking ball is to become effective out of the zone. The second, major step for a breaking ball is to become effective in the zone. That’s where Pivetta’s curveball might be. That’s what makes him look so exciting.

And even though Pivetta might not blossom into an actual ace, this is still a triumphant story of player development. A few years ago, Pivetta was the return in a Jonathan Papelbon trade. As Chris Mitchell wrote at the time, “[p]rospects with Pivetta’s statistical track record are a dime a dozen.” Before 2017, Eric Longenhagen considered Pivetta to be the Phillies’ No. 27 prospect. It seemed like there was a high probability he’d end up as a reliever. Yet recent progress has been steady, and consistent.

Nick Pivetta’s Development Season Age Level(s) BB% K% K-BB% 2013 20 R — A 9% 17% 8% 2014 21 A 7% 17% 10% 2015 22 A — AA 10% 19% 8% 2016 23 AA — AAA 8% 22% 14% 2017 24 AAA — MLB 8% 25% 17% 2018 25 MLB 3% 29% 26%

The strikeouts have only increased. We’re now seeing real signs of improvement in control. Pivetta has plenty left to prove, and he needs to show he can pitch this well against quality opposition, but it’s become clearer than ever that Pivetta is a real big-league starter. A real part of the Phillies’ future, along with being a real part of the Phillies’ present. The Phillies signed Jake Arrieta in part because they couldn’t fully trust their starting five. Now Nick Pivetta will try to help the team arrive a year or two ahead of schedule.