Jakob Junis was great yesterday, but he’s still built for the bullpen

Jakob Junis was really good yesterday. Like, really, really good. Junis gave up just a single hit in five innings, adding six strikeouts. In the 46 starts that Junis has pitched at least five innings, he has given up zero runs two times and a single hit just once. He did both on Wednesday afternoon.

So yeah, it was an exciting start to a season with so many question marks for the 28-year-old. And Junis has always been a second act kind of player. He was one of the top talents in the 2011 recruiting class and was getting heavily scouted at the professional level, but his draft stock dropped because he wanted to be a hitter, not a pitcher.

He was committed to play both ways at North Carolina State as an infielder and a pitcher and was asking for an $800,000 signing bonus to convince him to forego his dreams as a hitter. The Royals offered him a $675,000 bonus, and he obliged. Pitching was his backup plan, and it was a backup plan that took him all the way to the majors

But as exciting as it was, we shouldn’t be too quick to make him the fifth starter. Maybe his cutter is a real impact pitch that will reverse what we’ve seen from him over the past several seasons. But until we see that, we should lean on the data we have.

After strong performances in 2015-2016, he earned a spot in the rotation in 2017 that he wouldn’t relinquish for the next four seasons.

In those four seasons, only Danny Duffy has made more starts and pitched in more innings for the Royals. However, he was also largely ineffective. Among 112 qualified starters during that span, Junis ranks 93rd in fWAR.

His struggles are largely attributed to him being a two-pitch pitcher. 95.4% of the pitches Junis threw in 2020 were either a fastball or a slider. While there are starters that have found success with two primary pitches, the formula only works when both pitches are effective.

And for Junis, that has never been the case. Among qualified starters in 2019, Junis had the worst fastball in baseball. To be fair, the fastball was working yesterday, as Cleveland hitter went just 1-10 against his four-seamer. But this is the same Cleveland team that has scored the fewest runs in the AL this season and who scored fewer runs than ever AL team but Texas last season.

And the other variable in this equation is Kris Bubic. The young lefty was optioned to AAA after struggling in Spring Training in limited work. However, that demotion was also in part due to the Royals not needing a 5th starter at the start of the season.

It is absolutely true that Bubic struggled in the spring, but he also looked good in 2020. On the surface, he had a 107 ERA+ and struck out 22.1% of the batters he faced. As moderate as that is, Junis has never struck out batters at a percentage that high. And to dive deeper, his average opponent exit velocity was significantly lower than average to go with an above average soft contact rate.

Bubic is clearly favored in the Royals long-term plan than Junis and profiles far better as a starter than Junis. Giving Junis the fifth spot in the rotation almost certainly means that Bubic would lose his spot, which seems like a net negative for Kansas City, considering they started his service time clock earlier than most expected last season.

Regardless of where he winds up, Junis’ success will really come down to a few things.

The Fastball Must Stabilize

Since 2017, opponents have logged a whopping .274 ISO against Junis’ four-seam fastball. And in that same timespan, only six qualifiers have seen worse production from their fastballs. He was a full-throttle proponent of the Royals pitching philosophy to throw fastballs up in the zone in 2020, but he too often stayed in the middle of the plate.

He can be a good reliever with a dominant slider and a fastball that gets some extra velocity in the bullpen. But if he wants to take that last rotation spot, he’ll need a better long term fix.

The Slider Must Dominate

Junis’ slider is what makes his potential presence in the bullpen exciting. His slider is a plus pitch and the general principle is that a pitcher’s stuff only gets better in the bullpen. So Junis’ slider should be fully unleashed as a kraken pitch from the bullpen.

Ken Giles, Amir Garrett, Sergio Romo, and even Greg Holland are pitchers who have found good-to-great success with primarily sliders out of the bullpen. Junis can follow that formula. But as we’ve seen, that slider is missing an adequate secondary pitch out of the rotation, which makes this third factor all the more important if Junis wants to be a starter again.

The Cutter Becomes A Legit Offering

Pitches can succeed with below-average pitches if they can dilute their offerings with other pitches. Let’s just assume that Junis’ fastball isn’t going to take a drastic step after 500+ innings to sample from. Enter the new cutter. Over the offseason, Junis added the cutter to his arsenal at the advice of Royals pitching coach Cal Eldred. And the early returns have been good.

The glaring number from Statcast, alongside the absurd whiff rate on cutters, is the slider usage. He has thrown his slider 40% of the time over the course of his career, but yesterday, he threw it just 10% of the time and found tremendous success. It’s a small sample, but it’s great to see him succeeding with his secondary pitches early because we know just how good that slider will be as he increases its usage.

The bottom line: Junis’ new cutter could help him fight for a starting role if it is a legit pitch. And if the early returns are a sign of things to come, it could be a game changer. But it’s far too early to make that sort of evaluation.

What we do know is that it would be a tremendous asset in the bullpen along with his slider. We have seen failed starters move to the bullpen and become elite relievers. Unleashing Junis and his slider on hitters one inning at a time would not only be exciting to watch, but could also be his baseball calling.