Will these bullpen stints help Bubic, Kowar and the Royals pitching staff?

This year, highly touted pitching prospects Kris Bubic and Jackson Kowar have gone through their fair share of ups and downs within the Kansas City organization. Bubic and Kowar had strong months of May, albeit in Kansas City and Omaha, respectively. After making his MLB debut on May 2nd, Bubic performed well in May with the Royals, as he posted a 1.52 ERA and 1.11 WHIP in 29.2 IP. As for Kowar, in six starts with Omaha, he posted a 0.85 ERA and 0.88 WHIP in 31.2 IP, which also included a 33.9 percent strikeout rate, and a K/BB ratio of 4.10. Hence, Royals fans had a lot to look forward in the month of June from the two young pitchers, even in the midst of Daniel Lynch’s struggles in his MLB debut.

Unfortunately, both Bubic and Kowar have struggled immensely in the month of June, and it’s not surprising that the Royals’ fortunes as a team have also torpedoed as well (though Bubic and Kowar aren’t solely responsible; the offense carries a pretty large burden as well).

In four appearances this June, which included three starts, Bubic posted a 9.19 ERA and 2.17 WHIP in 15.2 IP, which ended up inflating his season numbers in those categories to 4.17 and 1.48, respectively. As for Kowar, his Royals debut has been pretty rough to watch, though he did show some signs of life in three innings of work against the Red Sox, which included a strikeout of Red Sox shortstop Xander Bogaerts:

Kowar failed to get out of the first inning in his MLB debut. In his second start against the A’s, he failed to get out of the second inning. He did pitch three innings today, but after getting through the first couple of innings unscathed, he did give up a two-run bomb to Red Sox nine-hole hitter, Bobby Dalbec in the 8th inning which pretty much put the game out of reach for the Royals:

For the year, Kowar is posting a 16.62 ERA and 3.23 WHIP in 4.1 IP. He has given up nine hits, eight runs, and five walks this year, and has only struck out two. While Saturday’s game was a step in the right direction for Kowar, he has not impressed at the Major League level like many Royals fans or prospect experts expected or hoped.

And thus, with Bubic and Kowar going through rough months of June, Royals fans have to wonder: will this bullpen experiment with Bubic and Kowar help the pair turn things around on the mound by the end of June and into July?


Bubic has been an interesting case this season. After getting knocked around in Spring Training and not making the Opening Day roster, Bubic has had two very different months in 2021, as I illustrated above. However, when taking a deeper dive into his numbers, Bubic has seen the BABIP monster catch up with him in June, something he managed to avoid in May.

Let’s take a look at the monthly splits this season from his advanced metrics via Fangraphs:

It’s interesting to see that Bubic has been better this may when it comes to striking batters out and walking fewer batters. However, Bubic has been a lot more hittable in the month of June. His HR/9 rate spiked from 0.30 to 4.60, and his BABIP also sharply inflated from .228 to .383. And lastly, his strand rate also regressed, as it went from 88.6 percent, which was pretty high, to 74.6 percent, which is more around league average (technically it’s 72 percent league-wide now).

Therefore, Bubic isn’t necessarily a worse pitcher in June than he was in May, it may be a correction (or at least regression to the mean) after such a hot start to the 2021 season. Notice the difference in xERA from May to June. It’s only a 19 point difference, and it was actually HIGHER in May than in June. That shows skill-wise, Bubic has a chance to be that pitcher again that he was in May. He just needs to make some adjustments when it comes to not keeping the ball in the zone so much

Hence, it makes sense why Mike Matheny and Cal Eldred would want to try get Bubic’s command back in a limited bullpen role. Not only would such a role limit Bubic’s workload, but it will also get him to pinpoint specific issues with his pitches in a lower-leverage setting. Let’s take a look at his swing and miss data from his last relief outing on Friday:

And let’s take a look at that same data set, but now from his last start on June 13th against the A’s:

It was promising to see Bubic utilize his fastball more and generate more strikes with it, as evidenced by the three percent increase in his CSW. While he did see his CSW rates on his changeup and curve drop a bit, he did generate more consistent whiffs. The whiff rate on his change was a promising development as well, as he generated as many whiffs on five changeups on Friday in comparison to the 15 changeups thrown on June 13th against the A’s.

Of course, this is one relief outing, so it is a small sample size, and Bubic hasn’t pitched in relief since May 13th. That being said, it will be interesting to see if Bubic will utilize his fastball more in order to develop it instead of relying so heavily on his changeup, which he was prone to do in his last couple of starts in June.


While Bubic has demonstrated some ability in relief this year, Kowar had never pitched in relief in his professional career until Saturday’s outing. Here is how things went for him in his three-inning outing against the Red Sox when it came to swing and miss data:

And now let’s look at his second outing this year against the A’s, where he went 1.1 IP at the Oakland Colisuem:

The nice thing about Saturday’s outing was that Kowar was finally humming with his changeup, which was his premium pitch in the Minors. After generating no whiffs on it against the A’s, and a CSW rate of only 7 percent in that contest, he generated three whiffs and a CSW of 41 percent against a solid Red Sox lineup. He was a little less effective with the fastball in his relief debut, as he only generated a CSW of 13 percent on Saturday after posting a 22 percent CSW rate against the A’s. However, he threw the changeup 14 percent more, which is a sign that this outing in a low leverage situation was much better for him when it came to having confidence in throwing his best pitch.

Kowar’s fastball and curve will always be interesting developments, especially since they each have had their issues in the Minors (his fastball can be too straight, and his curve has a tendency to hang too much). But perhaps a couple of more relief outings can get Kowar on track, much like it did for Bubic when he first started out in May.

When it comes to Kowar and Bubic, it’s likely that the Royals will keep them in the bullpen, at least for another two to three outings. As of now, neither pitcher has much to prove in Omaha, and I’m not sure if starting more games in Triple-A will necessarily help either Kowar or Bubic’s development. If the Royals really want to see what Kowar and Bubic can bring to the Royals in the future, they need to let them navigate the waters of MLB hitting, even if there are some growing pains. Casey Mize and Tarik Skubal of the Tigers are classic examples of rookie pitchers who got hit hard in their debuts in 2020, and are now seeing progress as sophomores in 2021. The Royals are getting some of that from Brady Singer, and hopefully, they can get it from Bubic and Kowar as well.

It’s been a rough June for both Kowar and Bubic, and even in their relief outings, they had their fair share of issues against the Red Sox.

But there are some positives…

And that is much needed for a club that hasn’t had many over the past couple of weeks.

Photo Credit: MLB.com

3 thoughts on “Will these bullpen stints help Bubic, Kowar and the Royals pitching staff?

  1. […] The stuff is certainly there for Kowar, and he has had some decent outings this year. He went six innings and struck out six while allowing only two runs on five hits and three walks on September 1st against the Indians, which showed that he can be dominant when his command is on. However, if he wants to ensure his place in the Royals starting rotation in 2022, he will need to show better control and command this Spring, or else it is likely that he will begin the year in long relief. […]

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