Lance Lynn versus the juiced ball

Lance Lynn, the Twins’ newest offseason addition, has pitched in five full major-league seasons and made more than 30 starts in each of them. Lynn had Tommy John surgery after the 2015 season, causing him to miss the entire 2016 season and giving his career a clean, easy-to-digest arc: five full seasons as a starter with no significant time missed in any of them. He only missed 2016.

Here are Lynn’s home runs allowed per season as a starter, beginning with 2012 and ending with 2017: 16, 14, 13, 13, Busted Arm, 27. That progression suggests one possible, tidy narrative for all the homers in 2017:

• (Cause): Lance Lynn just had major arm surgery
• (Effect): a not-quite-accustomed-to-pitching-with-a-reconstructed-ligament Lance Lynn gave up a bunch of bombs.

Unsurprisingly, this jump in long balls was reflected in Lynn’s home run per fly ball rate, which, in 2017, went from comfortably below league average to just above for the first time in his career.

Graph via Fangraphs

SABR-minded folks will tell you that HR/FB rates can fluctuate wildly year to year; a high rate in one season can be chalked up to bad luck. The next season, it could be crazy low and evidence of good luck. These things are hard to predict.

Last year Lynn did give up some cheap homers, as every pitcher does at some point. Of the 27 bombs he surrendered last year with the Cardinals, 13 of those types of batted balls — based on Launch Angle and Exit Velocity from MLB’s Statcast — are home runs less than 50% of the time. Roughly half of the home runs Lynn gave up last year weren’t usually dingers.

Take the first homer hit off him last season, from the Nationals’ Jayson Werth on April 11.

At 99 miles per hour and a 34-degree Launch Angle, that batted ball is a bomb 37% of the time, though Lynn certainly seems less than 63% optimistic about it.

Or take Jordy Mercer’s laser beam on June 24, which Statcast judged to have just a 13% chance of leaving the yard.

Cincinatti’s Scott Schebler hit two homers off Lynn last season, and this one, from June 7, tied Mercer’s 13% for the two lowest-probability batted balls to leave the yard against Lynn in 2017.

Gerardo Parra demonstrated Coors Field’s park effects in real time on May 28. This no-doubter had a 14% chance of being a round-tripper (in a, you know, normal park) based on its batted-ball profile, according to Statcast.

Paul Goldschmidt’s hit a towering bomb that had only a 43% chance of reaching the seats, but it did just that against Lynn on June 29 in Arizona.

Lest you think Lynn only ceded cheap dongs, I wanted to show y’all a couple legit ones.

Lynn allowed one batted ball — Christian Yelich’s 109-MPH, 29-degreed Launch Angle bomb on May 10 — that has been a home run 100% of the time since Statcast’s advent. Here is what a literal no-doubter looks like.

Yow. (Four-hundred and forty feet, if you’re wondering.)

Now it feels like I’m piling on, so I’ll just go ahead and show you one more homer that does have a bit of a silver lining: the batter, Logan Morrison, is now also a member of the Twins.

(Also, I like how Lynn goes full “freeze tag” upon realizing he just got rocked. One of my favorite pitcher home run reactions.)

So Lance Lynn had an anomalous home-run year in 2017 — yet his “back of the baseball card” numbers held relatively steady.

Lynn entered 2017 with a career ERA of 3.37; his 2017 ERA was 3.43. Lynn had made an average of 31.5 starts per season entering last season; he started 33 games in 2017. Lynn pitched an average of 189 innings per season during his first four years; he threw 186 ¹⁄₃ last year. Lynn’s career WHIP was 1.302 before he went under the knife; he posted a career-best 1.229 WHIP in 2017.

But how does a pitcher with a massive leap in HR/FB rate — while also adding walks and losing strikeouts — maintain a good ERA?

Graph via Fangraphs

Well, that’s one way to do it.

Lynn posted a .244 Batting Average on Balls in Play, more than 50 points below his career average and the lowest among all qualified pitchers last season. (Note for the pessimists: Ervin Santana was second.)

A lot of the analysis I’ve seen about Lynn entering 2018 docks him for the low BABIP, increased walks, and decreased strikeouts, but gives him a bit of a boost because his home run rate is bound to fall back down. He likely won’t boast a 3.50 ERA, but if he can throw 175 innings with a 4.50 ERA, the thinking goes, he’s certainly worth the $12 million the Twins gave him for this season.

But, in looking at Lynn’s aforementioned career trajectory, I thought that there may be one more possible explanation for his homer-filled 2017 — and one more reason to be skeptical he can limit home runs and runs in his first year with the Twins.

At the 2015 All-Star break, Major League Baseball — whether wittingly or not — changed the baseball. Between the first and second halves of the 2015 season, baseball saw the “largest increase in the rate of home runs/batted ball between a season’s first half and second half since at least 1950” (when data begins), according to the Ringer’s Ben Lindbergh. The home run rate has only risen since then. Last season, you may recall, MLB hitters set a new all-time record with 6,105 round-trippers, breaking the mark from the 2000 season — the apogee of the so-called Steroid Era.

If we return to the graph of Lynn’s career HR/FB rate, take a look at what happened while Lynn was rehabbing. (Represented here as the dotted line.)

Graph via Fangraphs

Due to the change in the baseball — and the logical, subsequent inducement for batters to try and get the ball in the air more often — home runs skyrocketed to theretofore unseen heights while Lynn was preparing his return.

Because Lynn missed the entire 2016 season, we have only the second half of 2015 and last season to see how he’s performed with the new juiced ball — a severely limited sample size.

But notice how Lynn’s HR/FB rate has risen in concert with the league’s. (You’ll have to imagine the dotted line here.)

Data via Fangraphs; graph via Louie

Writers who’ve analyzed the “Air Ball Revolution,” as it’s come to be called, have noted that it’s most benefited batters at the lower end of the home run spectrum. Yes, Giancarlo Stanton hit a truckload of dingers last year, but the power distribution has been more egalitarian than when Sosa, Bonds, and McGwire were regularly racing toward 70 homers.

Big boppers like Aaron Judge and Joey Gallo do not require the extra 10-15 feet that’s been tacked on the past 2.5 years to send their fly balls out of the yard. That type of distance benefits batters whose warning-track power has now become third-row power — and induces previously powerless hitters to try and get the ball in the air more often.

Just take a look at some of last year’s 20-homer hitters (there were an MLB record 117 of them in 2017, and 28 didn’t appear enough to qualify for the batting title): Eduardo Escobar (21 HRs), Jedd Gyorko (20), Ryon Healy (25), Tim Beckham (22), Didi Gregorius (25), Eugenio Suarez (26), to name a few. Scott Schebler, who I mentioned took Lynn deep twice last year, hit 30 bombs, for Pete’s sake. Point is: Back in my day, 20 homers used to mean something!

As Twins fans, we’ve seen Brian Dozier reinvent himself and make it his life’s work to try and lift every pitch into the air on his pull side — to great effect. Lance Lynn is a fly ball pitcher who has never had overpowering stuff, who relies on a relatively straight fastball for the majority of his offerings, and whose walks and strikeouts continue to trend in the wrong directions. His margin for error has always been minuscule, and, while he was gone, the league changed.

Here’s hoping that it hasn’t left Lance Lynn behind.