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Paxton was MLB's best 'air traffic controller'

Seattle lefty limited barrels, hard-hit balls in the air better than any starter
December 26, 2017

In the current era of baseball, the biggest battle between pitchers and hitters is being fought in the air.Hitters try to lift the ball, and pitchers try to combat the approach. We just saw it in the World Series, during which the Astros and Dodgers slugged a record 25 home

In the current era of baseball, the biggest battle between pitchers and hitters is being fought in the air.
Hitters try to lift the ball, and pitchers try to combat the approach. We just saw it in the World Series, during which the Astros and Dodgers slugged a record 25 home runs. We saw it in the regular season, in which hitters shattered the home run record and continued raising launch angles. There was another side, of course, as MLB pitchers set their own record for strikeouts and, according to baseball-reference.com, held scoring to relatively the same as in seasons past, despite all the homers.
It will become more imperative for pitchers to navigate those air balls moving forward, as hitters are learning they can do more damage in the air than on the ground. With that in mind, it's worth knowing which pitchers excel at beating hitters at "their spot." Statcast™ lists 134 starters who induced at least 150 air balls last season (i.e. any ball hit with a launch angle of 10 degrees or higher), and there was one pitcher whose name appeared at the top of the lists of best contact metrics over and over. 

Mariners left-hander James Paxton broke out in many ways last season, but his air-ball contact stands out. Among those 134 starters, Paxton allowed the lowest average exit velocity on air balls at 85.5 mph. He also allowed the lowest rate of air balls hit at or above Statcast™'s 95 mph baseline for hard contact, at only 26 percent. For context, MLB batters hit .623 and slugged 1.627 on "hard-hit" air balls last year, as opposed to a .253 average and .316 slugging percentage on anything softer. Lifting the ball is important, but lifting it and hitting it hard is much better.
The best air ball a batter can hit, from a Statcast™ perspective, is a barrel -- the optimal combination of exit velocity and launch angle that generally produces at least a .500 batting average and 1.500 slugging percentage. No full-time starter allowed a lower rate of barrels per air ball than Paxton, and Seattle's rising ace also allowed the lowest average distance. All of these factors funneled into Paxton's .366 expected weighted on-base average (or xwOBA, Statcast™'s most advanced metric that considers quality of contact when evaluating how pitchers and hitters should have fared) allowed on air balls, a mark that beat out National League Cy Young Award winner Max Scherzer for the lowest in our group of 134. MLB hitters posted a collective .461 xwOBA on air balls last year, meaning Paxton was nearly 100 points better than average.

Paxton became a big name in '17, but his air-ball control began blossoming the year before. Paxton allowed what was essentially a league-average .462 xwOBA on lifted balls over the first half of 2016, but lowered that to a .397 second-half mark that sandwiched him between Justin Verlander and Scherzer. Paxton's improvement here mirrored his improvement elsewhere, as a lower arm slot helped him hone his command. Paxton is one of the rare lefties who can reach the upper 90s on the radar gun and he appears to have raised his fastball location in 2017. A fastball with as much life as Paxton's should do well up at the letters, and his heater appears to have become a weapon against the trendy uppercut swing. The pitch gets even better when it's paired with a nasty knuckle-curveball like Paxton's.
Paxton improved in each Statcast™ metric listed above to become the Majors' king of air-ball contact, at least for one year. He also became one of the game's best starters at missing bats, meaning Seattle fans have a lot to be excited about in their potential ace.
The biggest question mark is Paxton's health. It's an issue that's plagued him throughout his big league career, but the Mariners believe his injury history is due more to bad luck than any single recurring issue. If Paxton can stay on the field, Seattle might have the most adept adversary to the air-ball revolution in 2018.

Matt Kelly is a reporter for MLB.com based in New York. Follow him on Twitter at @mattkellyMLB.