Health is the only real weakness in Paxton’s profile at the moment. (Photo: hj_west



In this, the year during which the all-time record for homers in an MLB season will be broken, there has been no shortage of dominant starting pitcher performances. From Clayton Kershaw to Max Scherzer in the NL to Chris Sale and Corey Kluber in the AL, true greatness has been on display. In this space not too long ago, I dug a little deeper into the exploits of Dodgers lefty Alex Wood. Today, let’s do the same in the AL and give Mariner lefty James Paxton his due.

I was in the draft room, a significant member of the decision-making team, when the Mariners selected Paxton in the fourth round out of Kentucky in 2010. He’d been drafted the previous season by the Blue Jays, but hadn’t signed. We were confident that we could indeed sign him; our area scout and crosschecking team had done quality work, and we had a solid working relationship with Scott Boras, his representative. What we saw was a high-upside lefty with top-shelf stuff, albeit with a checkered performance and health record.

We went back a ways with Paxton, who hailed from the Mariners’ backyard in British Columbia. I’d been responsible for overseeing Canadian amateur-scouting operations (among other duties) in my previous tenure with the Brewers. Canadian prospects have been heavily scouted by both the Brewers and Mariners for quite a while. Canadians represent an interesting population in terms of baseball talent: they graduate high school at 17, are disproportionately left-handed (frequently for hockey-related reasons), and aren’t subject to the same sort of heavy workloads as many of their U.S. counterparts.

Paxton matriculated at the University of Kentucky and showed flashes of brilliance. He’d strike out 10 over four innings and then give up seven runs in the fifth. His release point would suddenly waver, and all bets would be off. Still, you could envision a less athletic version of Steve Carlton at times. He featured a fastball in the mid- to upper 90s and a power curve: a pretty nice foundation to build upon.

After being limited to four indy-ball outings in his draft year, Paxton was brilliant in his initial pro season, whiffing 131 batters in 95 minor-league innings. Each season, I compile my own list of minor-league starting-pitching prospects based on K/BB and K/9 IP relative to league and level, adjusted for age. Despite not being particularly young for his level, he checked in at No. 11 on my list in 2011. When he was on, he was really on.

It hasn’t been a straight line to stardom for Paxton; he’s had a difficult time staying on the mound. After a healthy 2013 campaign (169 innings total) that culminated in four dominant MLB starts, he logged only 87 and 103 innings the next two seasons. He never suffered a truly debilitating injury, just a bunch of nagging ones. Again, his shortcoming is in the athleticism department. He was pretty healthy in a 2016 campaign split between Triple-A and the majors, and despite yet another DL stay this season, he has taken his game to another level when healthy.

Let’s dig into Paxton’s granular plate-appearance-frequency and batted-ball-quality profiles to see if his mainstream numbers offer a clear picture of his true-talent level.

In the tables below, this data is provided (current as of yesterday):

Plate Appearance Frequency Data POP % FLY% LD% GB% K% BB% Paxton 4.2% 26.7% 22.6% 46.5% 28.8% 7.0%

Contact Quality/Authority Data UNADJ C U-FLY-A U-LD-A U-GB-A ADJ C ERA – FIP – TRU – Paxton 76 37-41 80-94 135-117 81 64 54 64

The first table depicts Paxton’s K and BB rates, as well as the breakdown of all balls in play (BIP) by category type. For this table, I typically utilize color-coding to note significant divergence from league average. In this case, orange cells are over one STD above, yellow cells over one-half-STD above, blue cells over one-half STD below, and black cells over one STD below league average.

The second table shows Paxton’s Unadjusted Contact Score in the first column. This represents, on a scale where 100 equals league average, the actual production-level allowed on balls in play. Basically, it’s actual performance with the Ks and BBs removed. Unadjusted and Adjusted Contact Scores for each BIP category are then listed. Adjusted Contact Score represents the production level that each pitcher “should have” allowed if every batted ball resulted in league-average production for its exit-speed/launch-angle “bucket.” Finally, overall Adjusted Contact Score, actual ERA-, FIP-, and “tru” ERA- are in the rightmost columns. “Tru” ERA adds back the Ks and BBs, and incorporates the Adjusted Contact Score data, to give a better measure of Paxton’s true performance level.

There’s an awful lot to like in Paxton’s frequency profile. Obviously, his K-BB spread is quite eye-catching. A K rate over a full standard deviation above league average coupled with a BB rate over a half STD below affords one plenty of margin for error with regard to contact management. Even with an ordinary batted-ball-type/authority mix, such a pitcher typically would grade out as well above average.

Paxton has several other pluses, however. He’s always possessed a slight grounder tendency, and that has been in evidence this season. His grounder rate is in the average range, but his fly-ball rate is over a full STD below. Interestingly enough, he has managed to post a materially above-average pop-up rate despite the low fly-ball rate. This is fairly unusual and a major asset. He’s not only missing bats and generating grounders with his four-seamer, he’s also eliciting pop ups on it high in the zone. Good contact managers get either grounders or pop ups in large numbers. Very good ones can do both.

Let’s turn our attention to the second table above. Paxton’s Unadjusted Contact Score is a very impressive 76. Once we incorporate the exit-speed/launch-angle data, it becomes apparent that there isn’t an awful lot of luck at play in that number.

He’s only given up five homers this season, though some might say his home park contributes to that fact. Nope. Adjusted for context, his puny 37 Unadjusted Contact Score on fly balls barely moves upward to 41. His average fly-ball-velocity allowed of 84.8 mph is over two full STD lower than league average. He’s been almost as impressive at limiting line-drive authority; his Adjusted Liner Contact Score of 94 is quite strong, and his average liner-velocity allowed of 90.5 mph is over one full STD lower than league average.

Sure, the grounders he’s allowed have been hit harder than league average (117 Adjusted Contact Score), but those don’t leave the yard. He doesn’t allow many fly balls, and the ones he does allow aren’t going anywhere. The bottom line? If Paxton can get to 162 innings pitched, he has a real shot to be the AL Contact Manager of the Year (i.e. to post the lowest Adjusted Contact Score in the American League).

Oh, and he’s doing it despite allowing a higher-than-average liner-rate allowed. Liner rates are the most volatile among the major BIP types; it’s a decent bet that Paxton’s liner rate will regress downward between now and season’s end, making his overall numbers even better.

After adding back the Ks and BBs to his adjusted numbers, Paxton’s “tru” ERA- of 64 exactly matches his ERA-, and isn’t all that much higher than his FIP- of 54. That’s not quite in Sale/Kluber territory, but it’s pretty darned good.

Before we go overboard, however, let’s recognize the elephant in the room: Paxton’s well-established lack of durability/inability to stay healthy. He has obviously never pitched enough innings to qualify for an MLB ERA title and, at age 28, that’s at least a little bit concerning. He evokes memories of another pitcher from British Columbia, Rich Harden, who was dominant when healthy but wasn’t healthy very often.

Harden, a righty, qualified for his only ERA title at age 22. He showed dominance in smaller doses in a few other seasons, enduring major injuries along the way, much more serious than the ones Paxton has overcome to this point.

Still, health is arguably the sixth tool, and like just about everything else in this game, its trail leads right back to athleticism. A healthy James Paxton is a force of nature who could finally get the Mariners to October — and, at the very least, be really dangerous in a one-game Wild Card playoff. He’d be a really tough guy to dump big years and dollars into at this point, however. His track record suggests a lot more Harden than Carlton, but even in a limited run, he’s a fun one to watch.