The Curious Case of James Paxton

By CalvinChu
Jun. 27, 2016

In an era where sports fans rave about high K rates and low walk rates, and metrics, it’s rare that someone that fits the sabermetric bill isn’t considered an ace, and instead is a constant candidate for being designated for assignment.

Such is life for James Paxton, a super-prospect that was soon labeled a bust due to repeated injury. He finally made it to the big leagues at the ripe age of 24, still young enough to grow into a star, and he did not disappoint. Maybe it was being in a small market, but he still didn’t get much notoriety after two years of short stints in the majors. Last year, he ran into more trouble, but was still a decent innings-eater turning in an ERA under 4. This year, his peripherals suggest a reinvented player.

His Fangraphs suggests that he’s found a 3 mph uptick on his fastball year-over-year, which is always a good thing. In
Eno Sarris’ great article, he highlights how Paxton has changed his arm slot, going a little more Chris Sale-esque to pick up a few extra MPH, averaging near 100MPH on his fastball. He has also relied much more heavily on his new second-pitch, a slider (Fangraphs picks it up as a cutter, but regardless, it is a nasty pitch) and has cut back on his curveball, a pitch that he has struggled with this year. This has created a greater velocity difference between his fast stuff and his off-speed pitches, making both of them in theory more difficult to hit. In particular, Paxton’s strike-thrown percentage has seen a big jump. Paxton trails only the magical Bartolo Colon in %Strikes thrown amongst qualified starters. This has led to consistently getting ahead (or at least not falling behind) in counts vs. batters. More importantly, the contact percentage on balls thrown in the zone has dropped, suggesting that these strikes have been harder to hit than before, which explains his great jump in K/BB ratio, putting together the best ratio during his career thus far in both the minors and majors. His swinging strike percentage is 5% higher than last year, too.

But if he’s harder to hit now, why is his BABIP a sky-high .415?

In particular, batters have been more aggressive against him this year, swinging at more pitches. His swing-rate outside of the zone has jumped 10%, but has also jumped 4-5% for pitches in the zone, and since he’s thrown many more pitches in the zone, that may factor in on the amount of contact given up. 
However, contact doesn’t immediately translate to hits. But in Paxton’s case, it has.

He’s seeing a 5-6% weak-contact rate, about 10% lower than past years, but it’s likely that this number dropped because some weak contact has become complete whiffs, leading to the higher strikeout rate. However, his medium-contact rate, where most contact gets categorized, has jumped 13-14%, suggesting that maybe his faster pitches has caused batters to hack and hope for the best, with a relatively high degree of success.

Another interesting tidbit on his case is that players used to pull many of his pitches, but this year he’s reverted into a more balanced spray-chart-allowing pitcher. His percentages for groundball/flyball/line drive tendencies are not out of the ordinary, but yet his infield hit % is double what it has been in his career. This opened a rabbit hole for me: is Seattle’s defense subpar?

Ketel Marte, the M’s starting SS, leads the league in errors with 12, but supposedly that shouldn’t hurt Paxton’s ERA, but it might suggest a limited range. His WAR looks decent, as does Leonys Martin’s, but that is likely a function of Paxton allowing much contact right up the middle. Digging deeper, Fangraphs suggests that Marte is one of the worst defenders in the league, along with LF/CF Aoki, which then opens up to why perhaps Paxton’s contact has been falling between players with a more limited range. Nelson Cruz and Nori Aoki have been more than half a game below replacement player on defense despite only manning the outfield for part-time, and Seth Smith has been over a game below replacement level using the dWAR metric. Franklin Gutierrez has been marginally above average, but not enough to turn things around for the contact-happy Paxton.

Before, if players were pulling most of Paxton’s pitches, balls would fly towards Kyle Seager, a dependably above average defender. Now, it seems like maybe balls are flying towards less-dependable ones?

Lastly, and most importantly, let us take a look at the defensive players behind the plate.

The aforementioned jump in strikes thrown is happening despite the Mariners holding two of the worst pitch-framing catchers in the league, Chris Iannetta and Steve Clevenger. Both are steps down from the reasonably-above-average (defensively) backstop Mike Zunino, who is working on his offense down in AAA. His slashline is bloated, as it should be in the PCL, but is it enough to get the call-up post All-Star Break? Could a different signal-caller behind the plate, who helped with Paxton’s relative success in the last two years bring another level to Paxton’s performance? Per StatCorner, Paxton has the 5th highest % of pitches in the zone taken for called balls across MLB at 23% (nearly 4 times higher than the league leader) , and 10th lowest % of pitches outside of the zone taken for called strikes (4%, 3.5 times lower than the league leader), which suggests that he’s being forced to throw strikes further away from the corners, making them easy pickings for batters due to his catchers’ ineptitude at getting borderline calls.

Whatever the case, Paxton seems to be doing nothing particularly wrong, and should have a shot at turning in a stronger campaign the rest of the way, that is, so long as the Mariners keep handing him the ball.

For more, take a look at:

Seattle Team Stats
Baseball Reference James Paxton
James Paxton Fangraphs Page
Clevenger and Iannetta's struggles
Poor Iannetta
Bad Luck On Called Pitches
Mike Zunino Stats