The Royals bullpen has been an ongoing issue throughout the 2024 season. As a result, the group has often drawn the ire of Royals fans this year, and the group’s 24th-ranking ERA and 28th-ranking in WHIP certainly don’t help things.

GM JJ Picollo and the Royals’ front office tried to improve the bullpen at the Trade Deadline.

They acquired Hunter Harvey from the Washington Nationals and Lucas Erceg from the Oakland Athletics without sacrificing their major prospects (though infielder Cayden Wallace and pitcher Mason Barnett certainly have potential).

Erceg has lived up to the hype, as he has two saves, struck out eight, and walked zero in 7.2 IP with the Royals. Furthermore, his high-velocity stuff has been a much-welcomed addition to a bullpen that ranks second-to-last in the league in Stuff+.

Harvey, on the other hand, has been a disappointment.

In six outings and 5.2 IP, Harvey has seen his K rate go from 26.3% with the Nationals to 17.2% with the Royals, and his K-BB% go from 20% with Washington to 3.4% with Kansas City. As a result, his ERA and FIP are 6.35 with the Royals, and he produced a -0.2 fWAR before landing on the IL due to a back injury.

With Harvey’s timeline unclear, the Royals need a boost from the relievers in their organization, whether they are on the active roster or pitching in Triple-A. The Royals do not necessarily need “high-leverage” types, as Erceg, Kris Bubic, and James McArthur have handled things well since the Trade Deadline, as seen in the data set below via Fangraphs.

Could Carlos Hernandez be an option in the bullpen to boost the Royals?

Much like Harvey, he has a plus fastball and is coming off one of his best outings of the year on Friday against the Reds. After giving up a leadoff double, he struck out the side to close out the Royals’ 7-1 victory.

In his second outing since being promoted on August 10th, Hernandez showed impeccable control, which isn’t exactly a calling card for him as a pitcher.

Let’s examine the changes Hernandez has made since returning to Kansas City and how his presence (and Harvey’s absence) could affect the Royals’ bullpen for the remainder of the season.

Hernandez and His Pitch Mix Change

Hernandez was called up after Harvey and John Schreiber landed on the IL. Hernandez may only be a temporary option until Harvey or Schreiber return from the IL. If he continues to pitch well, it will be tough for Picollo to send him back to Omaha.

In two outings since being called up, he’s been sensational.

He has a K/9 of 15 in three IP, a 3.00 ERA, and a 0.84 FIP. They haven’t been high-leverage appearances (his other outing was during a Twins blowout of the Royals on August 12th). That said, it’s nice to see Hernandez limit the damage in his recent outings, something he’s struggled with the past two seasons.

An intriguing development for Hernandez in this recent call-up is that he’s been relying more heavily on his four-seamer and curveball and less on his slider and splitter. In his last outing alone, he threw his curve 15.8% of the time and his slider only 10.5% of the time.

For the season, he’s been throwing his slider 20.9% of the time and his curve only 13.2% of the time. However, in Omaha, his curve usage was 19.2%, and his slider usage was 12.9%. Therefore, the Royals’ pitching development team seems to have encouraged higher usage of the curve, and Friday’s outing was the first step at the MLB level.

The four-seamer has been his best pitch this year on a PLV end, but his other three pitches have had mixed results (especially his splitter, which has had poor pitch quality this year).

The slider and curve have been pretty similar at the MLB level. Conversely, the curve has shown better potential in Omaha on a pitch quality end, as seen in the MiLB pitch quality data comparison below.

As evidenced by his xZone%, Hernandez’s curveball was a much better-breaking offering for generating strikes. Furthermore, he also showed a better break with the curve in both the vertical and arm-side areas. It will be worth watching from Hernandez in this stint with the Royals if his Triple-A movement data starts transitioning to the Major League level.

The slider and curve both displayed a lot more horizontal break in Omaha than they did with Kansas City this year. We started to see more of that horizontal movement in Hernandez’s recent outings, especially in this strikeout on Friday night against Cincinnati’s Jeimer Candelario.

For context, let’s examine his curveball from late May when he pitched against the Twins at Target Field.

Hernandez’s curve is more of a vertical offering. However, it can be easily hit and hard to boot if it’s not located well. That said, the curve has a lower hard-hit rate (40%) than the slider (45%) and a lower wOBA (.244 to the .409 mark on the slider).

Utilizing the curve as his primary breaking offering could help Hernandez fully tap into his potential and be the backend reliever the Royals need in low to medium-leverage situations.

Who’s the Odd Man Out?

Schreiber is expected to return to the Royals soon as he is on a rehab assignment in Northwest Arkansas. As an opener, he looked solid as he struck out two in two innings of work.

It wouldn’t be surprising to see Schreiber return to the MLB roster when the Royals return home to Kansas City for their homestand against the Angels and Phillies next week. Thus, it’s possible that Hernandez could be back in Omaha by next Tuesday.

On the flip side, if the Royals want to keep up Hernandez, they must either demote a reliever or DFA one to make room for Schreiber.

The four likeliest candidates are Angel Zerpa, Will Smith, Chris Stratton, and Sam Long.

Regarding Stuff+ metrics, Zerpa and Long haven’t fared favorably since the Trade Deadline.

Zerpa has showcased the worst Stuff+ of Royals relievers since July 31st with a 90 mark, and Long’s 93 mark is the third-worst. Harvey has the second-worst mark, but one has to wonder if his back injury has significantly affected that Stuff+ number.

Surprisingly, Smith and Stratton fare well. Smith’s 149 Stuff+ on his slider has contributed heavily to his 113 overall Stuff+. Stratton has a 105 Stuff+, and his curve is his best pitch, with a 164 Stuff+ mark.

PLV rates the pitchers differently, with Smith and his slider rating worse according to Pitcher List’s pitch quality metric. Stratton has a poor fastball, according to PLV, but has three plus pitches. His sinker, slider, and curve rate well.

With Stratton, there’s a profile there that can lead to success. He needs to throw the sinker more and the four-seamer less.

Smith’s slider doesn’t rate as well, according to PLV. He locates it well according to the PLV characteristic data, but all the other traits of the pitch rate are below average, which explains his 4.96 overall PLV, which is below average.

As for Long and Zerpa, they both have their issues as well. Most of the pitches in their respective arsenals rate below average on a PLV end. However, Long’s slider rates well, which explains his surprising success with the Royals this year after a mediocre tenure in Oakland last season.

Zerpa’s sinker and slider are slightly above average, but his four-seamer and changeup rate are below average. Thus, Zerpa has the profile of a mediocre pitcher, and that is confirmed by his 5.05 PLV and his 10.29 ERA in seven innings in the second half.

If Hernandez stays up (and that’s not guaranteed), Zerpa or Smith may be the odd man out.

Zerpa seems the most likely option since he’s been so bad in the second half and has a Minor League option. Going to Omaha to work on some pitch shape and mix wouldn’t be the worst thing, and he could rejoin the club in September if Hernandez (or anyone else falters).

That said, Smith hasn’t shown much progress over the year, and his 4.93 ERA and 5.08 FIP are much uglier marks than Zerpa’s 4.46 ERA and 3.93 FIP.

Regardless, Picollo and the Royals will have to make a tough decision when they activate Schreiber off the IL next week.

Photo Credit:  Jay Biggerstaff USA TODAY Sports