James Paxton Primed to Dethrone King Felix as Mariners Ace

The Seattle Mariners finished second in the AL West with an 86-76 record. With a strong offense — they scored the sixth-most runs per game during 2016, led by Robinson Cano, Kyle Seager, and Nelson Cruz — the Mariners starting pitching lagged behind. With fans hoping for a bounce-back performance from Felix Hernandez, the King waned further, seeing an increase in ERA, FIP, and walk rate with decreasing number of strikeouts, first-pitch strikes, and swinging strikes. Hernandez was worth only 1 win above replacement, and at 30, it is unlikely the King will ever become the dominant pitcher he once was.

Despite logging only 121 innings, James Paxton pitched well, leading to a 3.5 fWAR, the highest among all Mariner pitchers. Paxton has always shown some upside, having strung along a 3.43 ERA and 3.32 FIP in 50 starts across four seasons. The 28-year-old has struggled to remain healthy, having only pitched 286 innings since 2013. Throughout the 2016 season, Paxton showed his best form.

Paxton averaged the highest fastball velocity for left-handed pitchers at 96.7 MPH. It was almost 3 MPH faster than the lefty ranked second, Robbie Ray. Among pitchers with 100 innings pitched, Paxton had the fifth-best FIP-, 17^th-best SIERA, and 21^st-best strikeout-minus-walk percentage. Furthermore, Paxton threw strikes. This was evident in his first-pitch-strike rate — 62.4% — and with the Mariners pitcher posting an elite 4.7% walk rate. Throughout the season, Paxton was unlucky, with a .347 BABIP and a strand rate hovering close to 66%. Paxton’s average exit velocity on line drives + fly balls was slightly above average. Couple that information in with a Deserved Run Average (DRA) of 3.09, and it is fair to say Paxton pitched fairly well and should have an impressive 2017 campaign.

One of the reasons for Paxton’s success? He changed his release points:

James Paxton Release Point Changes

In addition, Paxton’s cutter became one of his main pitches. Having reluctantly thrown it in years past, Paxton’s cutter was his second-most-used pitch and was quite effective. Among pitchers who threw 200 cutters, Paxton’s had the best whiffs per swing rate. Batters kept swinging, and they kept missing. It also boasted the lowest wOBA allowed in his arsenal.

James Paxton Cutter Vertical Movement

The big change in Paxton’s cutter, aside from the 1-mile increase in velocity: less rise (In 2014, Brooks Baseball classified the cutter as a slider). As the season wore on, Paxton also got more rise in his fastballs, leading to a greater induction of pop-ups. Paxton’s curveball was second in velocity among left-handed pitchers who threw at least 200. It featured an above-average ground-ball rate and swinging-strike rate.

Paxton showed significant growth during the 2016 season. With Felix Hernandez unlikely to return to his previous form, Paxton has the tools and ability to become the Mariners’ ace. The key for him will be to stay healthy in a pivotal season for both the Mariners and the 28-year-old pitcher.