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Mariners starter James Paxton is the real deal

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After big changes in 2016, Paxton has soared to the top of the league.

MLB: New York Mets at Seattle Mariners Steven Bisig-USA TODAY Sports

There are not that many starting pitchers out there who you can consistently rely upon every fifth day to make a solid start that gives your team a good chance to win. Of the starters that can do that, there are even fewer who are enjoyable and exciting to watch even if you’re not a fan of the team they play for.

James Paxton of the Seattle Mariners fits this bill perfectly, and thanks to recent transformations, he continues to get better and better while still only 28 years of age.

In just over a year’s time, Paxton has transformed from a low- to mid-level starter who could give you quality innings with limited consistency into an ace-level pitcher who is deservedly in the Cy Young conversation this season. He was also just recently named American League Co-Player of the Week on Monday and AL Pitcher of the Month for July. But what’s behind such a massive transformation in performance and results?

As detailed by FanGraph’s Eno Sarris last year, Paxton adjusted his release point, which lead to a career-high velocity of 97.4mph on his four-seam fastball. He finished the season third in average fastball velocity among those who tossed at least 120 innings last year, behind only Noah Syndergaard and Nathan Eovaldi. In fact, of the five different pitch types he threw last year, only the curveball didn’t set a career high in velocity, and that was by a tenth of a mile per hour.

Paxton’s Velocity

Pitch 2017 2016 2015 2014
Pitch 2017 2016 2015 2014
FBv 96.0 97.4 94.9 95.6
FCv 89.4 90.3 89.1 N/A
SIv 95.5 97.1 N/A N/A
CHv 86.9 88.5 86.7 87.4
SLv 87.5 N/A N/A 90.5
CUv 80.8 82.5 81.9 82.6
Pitch Info | Fangraphs

As much as I’d like to talk velocity, the velocity isn’t the sole reason Paxton is successful. Last year he set a career high in-zone rate with 47.5 percent of the pitches in the zone, and this year it’s up even higher, to 48.9 percent. His previous career high, besides the four starts he had in 2013, was 43.7 percent.

At the same time, he’s massively reduced his contact rate, setting career lows in both out-of-zone and in-zone contact rate, as well as career highs in-zone swing rate, first pitch strike rate and swinging strike rate. The only plate discipline metric that isn’t a career high this season is the out-of-zone swing rate which is down just a little bit over one percent as the chart below shows.

Pitch Info | Fangraphs

Throwing more strikes, and making opposing batters swing more often while making contact less often, is a really great way to pitch. One particularly helpful benefit to those sort of numbers is strikeouts. In 2014 and 2015 Paxton’s strikeout rate finished below 20 percent both seasons. Last year it finished at a respectable 22.9 percent and this year he’s sitting at a very solid 28.7 percent. Although he’s pitched almost 13 less innings than he did last year, he already has eight more strikeouts than his total of 117 last year, which was his career high.

Even though his walk rate is up from 4.7 to 7.1 percent, it’s hard to complain with the run prevention he’s exhibited as well as the fact that it’s still below his rate in 2014 and 2015 when it was over nine percent. When you strikeout guys at a near 30 percent clip, you’re going to walk a few here and there.

Last year was particularly important for Paxton, as he experienced the unlucky side of baseball that happens to everyone at some point. The chart below shows how his batting average on balls put in play (BABIP), has changed over the course of his career. Additionally, I added xFIP-, one of the metrics that tries to strip out luck and randomness, to show that despite an increase in BABIP recently (possibly caused by bad luck), his xFIP- has continued to drop.

Paxton had the second-highest BABIP among pitchers with at least 95 innings pitched last season, at .347. He also had a .276 batting average against which was also a career high. Even with a BABIP among the highest in the league, Paxton still kept the ball in the park, with a home run per flyball rate under 10 percent.

This year is totally different, as Paxton’s BABIP is currently at .303, which is much closer to the league average of roughly .300. His batting average against has also dropped significantly, as it’s currently .217. His home run per fly ball rate is even lower this year than the 8.2 percent it was last season, as it’s currently at 5.7 percent. This home run per flyball rate has him ranked second behind only Danny Duffy among pitchers with at least 100 innings this year. In other words, not only is Paxton striking out batters like wild, he’s also keeping them from doing damage when they do make contact.

Even with a batting average close to three hundred in 2016, he still finished the season sixth in FIP-, ninth in xFIP- and 20th in SIERA, while finishing 54th in ERA-. This year he’s improved all of those numbers — as the chart below shows — he’s currently second in FIP-, ninth in xFIP-, 10th in SIERA and sixth in ERA-.

Paxton’s Advanced Metrics

Year ERA- FIP- xFIP- SIERA BABIP
Year ERA- FIP- xFIP- SIERA BABIP
2014 83 88 93 3.80 .270
2015 101 109 108 4.44 .289
2016 94 67 79 3.54 .347
2017 64 55 74 3.43 .303
Fangraphs

His two best pitches by far this year are his four-seamer and knuckle-curve. His four-seam is second only to Boston Red Sox starter Chris Sale’s in total pitch value. His curve is ranked 4th in total pitch values, behind Lance McCullers, Jimmy Nelson and Stephen Strasburg. Of the six pitch types he’s thrown this season, only Paxton’s changeup has a batting average against that’s higher than .244, and his changeup is really only used against righties. Between his curve and four-seamer, Paxton has 98 strikeouts versus 26 walks which is a 3.77 strikeout to walk ratio. His cutter is also a pretty decent pitch as he’s racked up 31 strikeouts in 67 at-bats versus five walks, good for a strikeout to walk ratio of six. Really the changeup is the only pitch he’s struggled with, as far as results, since his ISO is below .110 on all other pitches and his slugging rate on all other pitches is below .355.

Ironically his pitch usage by count is almost the exact same as in the past. In other words, while he struggled at times last season while adjusting his mechanics, the sequencing on his pitches wasn’t, the cause as he’s been so successful this season with the same sequencing.


The fact that Paxton has transformed so drastically and so quickly across the board just shows you how valuable and unique he is. Paxton has done something most pitchers only dream about: rise up from the lower ranks of starters up to someone who teams would be killing each other to acquire. Not just that, he’s thrust himself into a Cy Young conversation, and even if he doesn’t finish among the top vote-getters, he’ll be included in the conversation into next season and beyond.

While fellow starter Felix Hernandez’s career is slowly winding down as he progresses further into his thirties and his career innings total surpasses 2,500 innings, the Mariners have someone who can take on a huge portion of the ace role and responsibility, if not all of it, in the form of Paxton. He is someone who Seattle can build around, as he’s under team control until 2021. And he’s one of the most exhilarating and entertaining starters currently in the game.


Ron Wolschleger is a pitchaholic and a Contributing Writer for Beyond the Box Score as well as Bless You Boys. You can follow him on Twitter at @FIPmyWHIP.