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What Taijuan Walker and the 2020 Mariners can do for each other

Not many rumors have swirled around the Mariners this winter, but a reunion with their former top prospect has been hinted at.

Arizona Diamondbacks v St Louis Cardinals

Despite the quietest offseason in Jerry Dipoto’s tenure, the Mariners have been involved in a few rumors. They were recently outbid by the Dodgers for former Brewers RHP Jimmy Nelson, who was one of a couple pitchers Seattle has been connected to in contract negotiations, per MLB’s Greg Johns. The other is a more familiar name - Taijuan Walker.

Sidelined with Tommy John surgery in mid-April of 2018, Walker’s rehab was lengthy, lasting a full 17 and 12 months before he finally returned for a single inning at the end of September 2019. TJ recovery in the past decade or so has tended to require just a 10-12 month recovery, as well as a more consistent return to form. Not so for Walker, whose UCL tear was unfortunately quite large. In his lone 2019 appearance, he showed a baseline of health, with his velocity back around 2017-2018’s level. The Diamondbacks decided he wasn’t worth the hair over $5 million he’d have been due in arbitration, and with a glut of rotation options themselves and an eye on contention, left Walker to be someone else’s project. Hopefully, that someone will be the Mariners.

The 27 year old Walker spent the first seven seasons of his 10 years as a professional with the Mariners organization, including parts of four of his seven years in the majors. He’s never reached the ceiling hinted at with three straight seasons - 2012-2014 - of ranking in the top-20 prospects in baseball, finishing as high as 11th before 2014. Still, Walker debuted at the age of 20, and had seen his numbers improve each full season before injury wiped away most of the past two years. Pitchers tend to see their velocity dip a shade as they age, but improve in command, off-speed utilization, and the ethereal but still-important maturity and knowledge of the league.

We can address the ambiguous part quickly up front. There were grumblings about Walker’s maturity during his time in Seattle, founded or not, but no such rumors emerged from his time with Arizona. The now-father has publicly hailed at least one of the Mariners’ recent staff additions, and by all accounts has a positive reputation as a teammate. When I was 21 I felt a shot of Everclear was a reasonable start to most Friday nights. Nearly five years later I do not. That’s growth, and it’s appropriate to expect of Walker, like most young players. To the tangibles!

Baseball Savant

It’s important to remember that 2015-17 are each 130-170 inning samples, while 2018 and 2019 are 13.0 and 1.0 IP respectively, but we see mostly-consistent fastball velocity with a settling point just shy of 94 mph the past few years after emerging on the scene at 95. It’s still above-average heat, but it needs some help, and it’s not really getting any. Walker mostly ditched his sinker by 2017, leaving him with a mix of four-seam, splitter, cutter, and curve(r). The four pitches have the opportunity to complement one another brilliantly, but they just haven’t. The first thing Walker and the Mariners will want to identify is how to get more out of his non-four-seam options.

Walker’s curveball generated swings and misses on over a third of the swings it lured in 2017, but it only drew swings one third of the time it was thrown, and was only in the strike zone a shade over a third of the time for that matter. Whiffs make the baseball world go ‘round, but despite brilliant numbers on his rise through the minors, the rest of MLB has caught up to him. He’s struck out 21.3% of batters for his career, which would’ve been above league-average in 2013 (19.9%) but now is even further below 2019’s typical rate (23.0%). The four-seam/curveball combo is in vogue right now in pitch design, as the two pitches offer counterbalancing spin that, when used well (like, say, Tyler Glasnow, as is shown in an article published just this morning by FanGraphs), can be deceptive in the way we often think of fastballs and changeups pairing up. Even with what has mostly been an average spin fastball, tunneling and mirroring the movement profiles of a fastball and curveball helps create deception.

Thanks in large part to inconsistent mechanics, unfortunately, that’s been nigh-impossible. Below is Walker’s 2016-2018 release points, broken up by year.

Baseball Savant

The initial look is jarring from 2017-18, but there’s a catch. Walker predominantly set up on the 1st base side of the rubber for much of his career (clip for reference), but was shifted to the middle/3rd base side in his few 2018 appearances (clip for reference) before injury ended the season. Still, there’s a significant degree of variation within each season.

There were already question marks about Walker’s long-term rotation chops back in 2015 thanks to his struggles with release consistency. Most notably, his splitter - functionally his changeup despite its upper-80s/lower-90s velocity - has maintained essentially an entirely different release than his other pitches, which was noted as a concern half a decade ago as well. Here’s a 3D rendering of the average release points on Walker’s offerings from his 2017 season, when he last threw around a full season.

Red: Four-seam, Lighter Blue: Curveball, Orange: Cutter, Greenish-Blue: Splitter
Baseball Savant

This confirms what we saw in the cycling chart above, but gives us a different way of visualizing it. Ideally the four-seam and the curveball would come out as close to one another as possible. Heck, ideally they’d all come out as close as possible, but at least those two could pair well. Similarly, given the cutter and splitter not only sharing a near-identical velocity space but offering almost mirrored movement profiles, it could be extremely advantageous to get both those lined up similarly as well.

Walker’s move on the rubber could help him get a bit more deception against same-handed hitters, but lefties would theoretically stand to gain from a better look at off-speed. My inclination would be to stick with the shift and focus on pairing the fastball/curveball and cutter/splitter combos. Walker’s injury is undoubtedly detrimental for him, but working back from significant down time does offer the opportunity to retrain muscle memory that had been long-engrained. Perhaps this can be a catalyst for him and the Mariners to craft a motion that lets his best features shine.

Considering the Mariners have cut payroll drastically and have yet to reinvest meaningfully to improve their rebuilding roster, there should be an expectation of far more than signing Walker alone. But given the precedent of two-year deals for talented pitchers coming off TJ, as well as the Mariners’ glut of intriguing pitchers who need 20-25 starts, but likely can’t be expected to deliver 180-200+ innings, Walker is an ideal match. The 26-man roster greases the wheels further, as Seattle will likely run a six-man rotation at times in 2020, with Marco Gonzales, Yusei Kikuchi, Kendall Graveman, Justus Sheffield, and Justin Dunn as the current group but few quality big league innings assured. Oftentimes a nostalgic reunion is heart over head, but this is a pairing that makes too much sense not to come together. Make it happen, Jerry.