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Sailor’s Delight: Examining the best start of Justus Sheffield’s career

Justus Sheffield has been a real “Sheff’s kiss” in Arkansas and it’s time we asked if we believe it

MLB: Seattle Mariners-Media Day
That Spring look
Jayne Kamin-Oncea-USA TODAY Sports

Justus Sheffield took a no-hitter into the 8th inning in his third AA game last week. He finished with 8 strikeouts, 1 walk, and only 1 run allowed. It was the longest outing of his career and the most Ks of the season. If any other 23-year-old pitcher in our system had shown this kind of stuff in a AA game, the fanbase would be ecstatic. Yet, it doesn’t feel like a victory. Not when two months ago Sheffield had worked his way into the major league rotation. Not when he walked 41 batters in 55 AAA innings. Not when he was the key piece in an offseason trade for our brightest and most Canadian trade chip.

Not when the former Top-25 Prospect has fallen in the the back half of the Top-100.

So, are a few good starts in Double-A really worth believing in?

In order to choose one of these options we need more information. In particular, information that will help us answer these questions:

  1. How and why did he struggle in AAA?
  2. How and why is he succeeding in AA?

If the answer to the second aligns with the answer to the first, then I believe we can say that these results are meaningful. If not, Justus may be skating by on the nastiness of his stuff alone.

The AAA struggles were fairly straightforward. One need only take a quick peek at his 6.71 BB/9 and his 26.7 HR/FB% to understand that Sheffield wasn’t able to locate his stuff. And, when he threw strikes behind in the count, the PCL baseball (juiced more than a Bash Brother) went directly into the ocean.

Jerry Dipoto elaborated on Episode 53 of The Wheelhouse that he thinks Sheff’s mechanical problems are a symptom of mental processes, of not being able to relax or control his breathing, prompting his body to get out of sync. Dipoto listed three things for Sheffield to work on: “Learning how to control the pace of his game on the mound ... winning 1-1 counts ... and controlling the walks.”

Sheffield, too, is aware of what he needs to change. “It’s just throwing it over the zone,” said Sheffield in an interview with the Seattle Times. “Trusting the stuff and letting the hitters get themselves out.”

Trust. That is the theme of the comments around Justus Sheffield. You can understand how a young pitcher getting his mistakes blasted over the fence could lose trust in their ability to get hitters out. His demotion to a more pitcher-friendly league was intended to rebuild that damaged confidence.

So far the results are everything we could hope for.


Sheffield is pitching deep into games, racking up Ks, and keeping the walks to a career low. That checks every item on the list. Still, it’s against AA hitters. Still, I am skeptical.

I re-watched every pitch of his dominant almost-no-hitter to try and parse out if the process in the best start of his career was as good as the results.

Like most things in life, it was a little of both.

Early in the game Sheffield was throwing strikes, which is good, but it was more control over command.

This was a common picture.

The location is set up down and in at the batters knees.

The resulting fastball leaks up above the belt and out over the plate. Luckily, thrown at 96 mph to a Texas League batter, it resulted in a lazy fly ball.

It’s not uncommon for even elite pitchers to miss their spots—it’s hard to hit spots. But Sheffield made a habit of missing up with his fastball and the Drillers players made a habit of missing them or hitting underneath them. I can’t help but feel Sheffield was getting away with pitches because of movement and velocity that may have left a PCL park.

But that’s why he’s there, right? To not be punished for small mistakes, to gain confidence so that he doesn’t feel the need to be perfect, to believe in himself?

Three innings later we see the early success and the larger margin for error begin to change his process.

That same spot as before, same side of the plate, same height.

Gotcha. The pitch ends up only a few inches from the spot, making for an easy frame for a called strike. It also set up the next pitch, a nasty slider off the plate for a swinging strike.

Here’s another example of late game and confident Sheff in gif form.

Don’t stop

He buries an 0-0 slider, missing his spot but missing it low with nasty movement.


Here the Sheffield of Nottingham comes back with a fastball at the bottom of the zone that may have been a strike had Odom (who is very good behind the plate) been able to snag it. It is now 1-1, the very count he’s supposed to win.

Hold on to that feeling

Odom wants that same pitch and Sheffield paints his spot beautifully. He seems more in control as well, touching his back leg down instead of swinging it from his momentum. The added body control may mean he took a few ticks off the fastball to hit his spot.

Streetlights, people, etc.

They go back to the slider at the bottom of the zone here and it produces an emergency half-swing for a foul. The next pitch would be a low fastball hit right back to Justus for the easy out.

The thing that is encouraging about this AB, and others like it, is that Justus stayed in control. He worked his sinking fastball at the bottom of the zone and mixed in his slider, all with consistent command.

The most impressive pitch, to me, was the 1-1 fastball at the bottom of the zone. The organization wants Sheffield—and all pitchers—to win 1-1 counts. This makes sense, as after 1-2 counts pitchers have an average FIP of ~1.6, while in 2-1 counts it’s ~5.8. Losing a 1-1 count is more extreme than the difference between replacing Max Scherzer with Aaron Sanchez. Sheffield took his time and didn’t try and blow a nasty fastball past the hitter; he held back and threw a quality strike. Whether because of skill or the rabbit ball, he just wasn’t able to do this consistently in AAA.

The night wasn’t perfect, though. I don’t know how often he threw his change, if at all, and only 13 of the 27 batters received a first pitch strike—under 50%. The lowest first pitch strike thrower in the majors is Luis Castillo at 51%. Even in his best, most efficient outing Sheffield was having trouble getting ahead.

Faith, confidence, belief—these are all squishy things to evaluate. Yet they contribute a great deal to sports and, likely, Justus Sheffield’s ability to be a successful pitcher. How do we talk about the development of someone’s faith in themselves? How do we measure something so fluid and ineffable?

We can’t.

What we know is that Sheffield’s results have been outstanding, even if his process is still in development. We know that the Mariners wanted him to control the game, win 1-1 counts, and limit walks—all of which he’s done at Double-A, even if he struggled with that at Triple-A. We know that time and sustained success usually contributes to confidence. We know that he is young. We know he has been smiling.

Sheffield likely needs more time and more sustained success in a lower-pressure environment in order to gain that confidence. We’ve seen what happens when he over-throws, when he tries too hard to be perfect. But if he can relax, win counts, and learn to trust in himself?

We could get used to seeing this.