From the start of his career through 2017, Paxton allowed only 0.7 home runs per nine innings. This season, he surrendered 23 homers in 160.1 innings, or 1.3 per nine frames. Pitchers like Masahiro Tanaka and CC Sabathia have had success in the Bronx despite giving up dingers at a similar rate, but they’re also not necessarily frontline starters like Paxton is expected to be.

More fly balls usually means more home runs, and that’s precisely what occurred to Paxton this season. Historically, Paxton has generated tons of grounders when he wasn’t striking out batters. In 2018, he gave up more fly balls than grounders for the first time in his career, and subsequently, more homers than ever.

It’s not totally clear why Paxton’s batted ball profile changed. His pitch location is basically the same (2018, 2017, 2016). Maybe, just maybe, one could argue that he’s elevating his pitches a tad more, but really, he basically challenges opponents to hit his fastball. Those linked heatmaps are pretty much all dark red over the middle of the plate. In terms of pitch selection, Paxton hasn’t wavered either. He predominantly relies on his fastball and cutter with a few curveballs mixed in. Certainly, the league’s hitting environment has changed, but why didn’t that affect Paxton when the fly ball revolution began in earnest in 2017?

If Paxton is truly a fly ball pitcher going forward, he’s going to continue to allow home runs, especially in Yankee Stadium and the AL East. On the bright side, maybe Paxton’s home run to fly ball rate is due for some regression. The 14.4 percent mark is comfortably above league average and way out of line with Big Maple’s career norms. If Paxton was league average (12.7 percent), he’d have allowed 20 homers in 160.1 innings, or 1.1 per nine innings. At ten percent, which is a little closer to his recent marks but not quite as good, he’d have given up 16 long balls, or 0.9 per nine innings.

Aside from some home run rate regression, DRA gives Paxton another vote of confidence. Despite 2017 being better from a results standpoint (i.e. ERA), the southpaw’s DRA that year was virtually the same as this season. He had a 2.63 DRA in 2017 and followed it up with a 2.67 mark this year. It’s quite a bit easier to rely on those marks than upon me pontificating about Paxton’s home run to fly ball rate!

There’s no debating that Paxton will be a good pitcher for the Yankees next season. The real question is: how good will he be? Aside from health, home runs allowed will likely tell the tale of Paxton’s career in pinstripes. If he essentially repeats this season, he’ll be a very good mid-rotation starter. If he regresses a bit or lives up to his DRA, he’s unequivocally an ace.

Batted ball rates from Fangraphs. Pitch heatmaps from Baseball Savant.

Bronx’s budding star sits ahead of  titans on the velocity front, eclipsing names like Stephen Strasburg, Chris Sale, and Jacob deGrom. Severino’s average fastball velocity of 97.7 mph this season is one half mile per hour ahead of Gerrit Cole and more than a full mile per hour ahead of James Paxton. If the city of New York was looking into alternative sources of energy to power the city, they might want to tap into this 23-year-old’s electric heater.

Fellow BP Bronx writer Austin Yamada astutely pointed out the widening of Severino’s ‘velocity gap’ between his fastball and his primary offspeed pitch, the devastating slider we’ve come to love (Yamada also made a great comparison to Rays’ ace Chris Archer, which I cannot steal from him, but sure as heck want to). I’m here to also point out the other velocity gap that widened since last season and has led Severino to the promised land of left handed hitter domination.

An issue with simply looking at percentage pitch usage is that we often glaze over changes in how a pitcher is throwing a certain type of hitter. We may look at the aggregate usage of a certain pitch versus all hitters and see a decrease, but remain blind to an increase when splitting up the usage by a simple factor like left handed versus right handed bats.

This theory of mine applies conveniently to Severino. On the left below we have Severino’s change in changeup usage to all batters between 2016 to 2017. Our graph on the right shows his changeup usage just to left handed bats between 2016 to 2017.

Sure it’s a small fraction of an increase, but that uptick is important, especially if you look at how virtually unhittable the pitch has been to left handed bats…

Lefties possessed a .263/.331/.416 off Severino in his 71 innings of work, which has bottomed out to a dismal .178/.213/.352 so far in 2017. Trusting his changeup more to lefties has allowed him to escape the tag of a pitcher with heavy lefty/righty splits, forcing managers to rethink throwing a lefty heavy lineup at the Yankees’ young star and praying for a few misplaced offspeed pitches.

Severino has tinkered with his approach to both sides of the plate, and it’s working. More changeups and fastballs to lefties, more sliders and virtually no changeups to righties.

Back in Januray of last year, the great Jeff Long called back to a Baseball Prospectus column by Harry Pavildis that broke down what makes a good changeup. You can read the article here, but I’m going to cherry pick the high level points Long summarizes in his column. There are four factors in a pitcher’s repertoire that help to make a changeup effective.

1. Faster fastballs result in more whiffs on the pitcher’s changeup.
   1. Severino’s velocity is up (96.7mph to 97.7mph from 2016), but he isn’t seeing a noticeable increase in either his swinging strike rate or strikeouts as a whole with his changeup (whiff % is down, 7.3% to 3.6% from 2016 to 2017).
2. “Velocity gap,” or the difference between a pitcher’s fastball and changeup velocity also results in more whiffs.
   1. This gap for Severino has increased a noticeable amount, just like his fastball-slider velocity gap. In 2016 this difference was about 7mph. This season it’s up nearly 3mph, to just under 10mph of difference between his fastball and changeup.
   2. Oddly enough, even though Severino is 2-for-2 on these changeup traits, we’re still sitting on a decrease in whiffs with the pitch.
3. Pitchers with higher changeup whiff rates, throw their changeups more.
   1. We have to disqualify Severino on this one because as I’ve already pointed out twice, Severino’s changeup whiff rate has actually decreased. We’ll get to the bottom of this, I promise you.
4. The vertical drop of changeups relative to fastballs increases both the whiff and groundball rate.
   1. This is a factor we haven’t touched on with our young stud, but a good one to consider. Severino’s changeup vertical movement increased from 5.6″ in 2016 to 6.9″ this season (more “sink”). With his fastball vertical movement steady from 2016 to 2017, the extra sink on his changeup relative to his fastball can add more whiffs and grounders to the pitch’s results.
   2. Ah! There is what we have been searching for. More grounders! Severino’s changeup has in fact seen a nice increase in grounders per ball put in play. Last season it was at 46.2% while this season it has edged up nicely to 54.6%.

One more thing to consider in order to further understand why we’re still not seeing more whiffs with the changeup is to realize the velocity at which Severino is throwing his changeup.

In the article I linked to above from Jeff Long, he mentions the wonky relationship between whiffs and grounders with changeups, noting that changeups with higher velocities actually result in more groundballs realtive to whiffs. Our big takeaway here is that even with the nice drop in velocity on Severino’s changeup, widening the velocity gap between the pitch and his fastball, the pitch itself is still a high velocity offering compared to the rest of the league. At 87.9mph, he has the 15th hardest changeup in the league among starters who have thrown the pitch 50+ times.

Nestled right in the 83rd percentile for changeup velocity, the overlooked pitch of Severino’s arsenal deserves some respect as it has kept him honest against left handed bats. With the concept in hand that higher velocity changeups lead to more groundballs, I’m not concerned one bit that Severino isn’t getting enough swinging strikes to maintain his success against left handed bats. Combine this with the increased velocity gaps between both his fastball-slider (previously discussed by Austin Yamada), and his fastball-changeup discussed here, and it’s no surprise we’re looking at a pitcher with a pristine 1.64 DRA.

If the season started tomorrow, the Yankees’ starting rotation would look something like this:

Masahiro Tanaka
Luis Severino
Michael Pineda
Nathan Eovaldi
CC Sabathia

Ivan Nova
Bryan Mitchell

Now that’s not so bad. All seven of those guys have had some degree of success one time or another and could contribute in 2016. As a bonus, six of the seven are younger than 30 years old. But, like last year, the rotation carries a number of question marks. Will Pineda be healthy? Will we see the version of Sabathia that dominated September or the one that struggled through April, May, June and July (and that’s not even touching on the fact that he’ll be pitching for the first time since checking into rehab last October)? Can Nova bounce back from a bad season? Is Mitchell truly an MLB-caliber starter?

Given the uncertainty, it’s likely the Yankees will add to their rotation before Opening Day. And given their apparent commitment to youth and austerity, we can assume they’ll look for a young, cost-controlled option. But young starters certainly don’t grow on trees, and any team that has a 25-year-old, mid-rotation pitcher won’t likely part with him easily.

With Shelby Miller off the board and Jose Fernandez’s price prohibitively high, let’s look at some young pitchers Brian Cashman might think about placing calls on.

Category I: The Deep Rebuilding Team

Though most rebuilding teams want to hold on to their mid-20s players, occasionally a team embarks on a teardown so thorough it will part with even its young major leaguers. Here, we’re looking for pitchers young enough to help the Yankees in the near future but old enough that their current teams are willing to cash in for prospects.

• Julio Teheran, Atlanta Braves

The Braves have already traded the 25-year-old Miller and 26-year-old Andrelton Simmons, so they would probably be willing to part with the 24-year-old Teheran for the right price. This would be somewhat of a buy-low move, as the righty is coming off an unimpressive season on the heels of two good ones. Teheran would cost the Yankees at least one of their top prospects (Aaron Judge, Greg Bird, Jorge Mateo), but unlike Fernandez wouldn’t require a package built around Severino.

• Taylor Jungmann, Milwaukee Brewers

Jungmann had a nice rookie year in 2015 (3.77 ERA, 3.92 FIP in 119.1 innings), but he’s already 25 years old, and the Brewers aren’t anywhere close to contention. There’s no specific indication that the 2011 first-round pick is available, but he’s the type of low-ceiling guy a rebuilding team might consider moving under the right circumstances.

• Anthony Desclafani/Rasiel Iglesias, Cincinnati Reds

This could be a stretch, but the Reds have a ton of young arms, and maybe they’d be willing to part with one of the older, more developed ones. Desclafani and Iglesias are both almost 26 with solid rookie seasons under their belts. Would Cincinnati give up guys who don’t hit arbitration for a few more years? Who knows, but it’s probably worth a call.

Category II: The Low-floor/high-ceiling guys

The Yankees could pursue a young starting pitcher whose previous teams are ready to move on following early-career injury or ineffectiveness.

• Henderson Alvarez, free agent

The Marlins non-tendered Alvarez only a year after he posted a 2.65 ERA and 3.58 FIP over 187 innings, which indicates an enormous lack of confidence in his ability to come back strong from shoulder surgery. Still, the 25-year-old has shown he can pitch at an elite level and will offer high-risk upside to whoever signs him.

• Matt Moore, Tampa Bay Rays

The Rays are supposedly discussing trades involving the 26-year-old Moore, who has thrown only 73 innings in the past two years. Once upon a time, Moore was one of the top three prospects in baseball along with Mike Trout and Bryce Harper, and the Yankees (along with everyone else) will be tempted to try to recapture that potential.

• Tyler Skaggs, Los Angeles Angels

Skaggs hasn’t lived up to his top-prospect hype, with a career 4.72 ERA in 181 innings, but his 3.55 FIP in 2015 suggests a breakout could lie ahead. The Angels have more starting pitchers (Garrett Richards, Andrew Heaney, Hector Santiago, Matt Shoemaker, Jered Weaver, C.J. Wilson) than they know what to do with, so perhaps they’d consider dealing the 24-year-old Skaggs.

Category III: May I interest you in Brett Gardner?

The Yankees’ willingness to trade Gardner opens up the possibility of working with a contending team that simply needs an outfielder (plus some prospects) more than a starting pitcher.

• Taijuan Walker/James Paxton, Seattle Mariners

The Mariners have already reportedly turned down a deal centered around Gardner and the 23-year-old Walker but are open to giving up 27-year-old James Paxton. Given Seattle’s need for outfielders, this one makes enough sense for the teams to eventually find some middle ground.

• Danny Salazar/Trevor Bauer/Cody Anderson, Cleveland Indians

The Indians are reportedly listening to offers on all their starting pitchers, and though Carlos Carrasco’s price tag is likely greater than the Yankees are willing to pay, Cashman could make a move for Salazar, 25, Bauer, 24 or Anderson, 25. One of these deals could require forking over some good prospects in addition to Gardner, but the 32-year-old left fielder could be an appealing target for an offense-starved Cleveland team.

• Zack Wheeler, New York Mets

The Mets have an excess of young starting pitching, and the 25-year-old Wheeler, coming off Tommy John surgery, could be the odd man out. The question is, does Sandy Alderson need an outfielder to replace Yoenis Cespedes, or are they content to start the season with a Michael Conforto/Juan Lagares/Curtis Granderson alignment.

Lead photo courtesy of Steve Mitchell-USA TODAY Sports