Four metrics to pay attention to from Royals Middle Infielders in 2020

Now that baseball is back, it seems appropriate to post about the 2020 season again. Previously, I had written posts about certain advanced statistical metrics to pay attention to for Royals starting pitchers and Royals outfielders. In this post, I am going to focus on Royals middle infielders, and what metrics Royals fans should be paying attention to once the regular season gets going in late July. During a shortened season of only 60 games, advanced metrics may be even more important, as they could be indicators of what kind of streaks (both good and bad) are sustainable during a much shorter 2020 campaign.

For Royals middle infielders, I am going to focus on only four: shortstop Adalberto Mondesi; second baseman Nicky Lopez; utility infielder Erick Mejia; and utility infielder Humberto Arteaga. I do know that Major League Baseball will be expanding to 30-man active rosters with a corresponding 30-man taxi squad. And thus, it is likely that middle infielders such as Matt Reynolds (a free agent non-roster invitee) and Gabriel Cancel (not on the 40-man, but a Royals draftee and Spring Training invitee) will make one of the rosters (with taxi squad being most likely).

That being said, while Mondesi and Lopez seem slated to be starting up the middle for the Royals on Opening Day, it is hard to see any other Royals middle infielder in the system outside of Mejia or Arteaga getting much play at the MLB level in 2020. Even if Lopez struggles, it seems like it will be more likely to see Whit Merrifield move back to second than Mejia, Arteraga, Reynolds, or Cancel get a full-time shot. And thus, I decided to focus on just those four, and metrics regarding to those four middle infielders, referencing data from Fangraphs from last season.

So let’s take a look at what individual metrics Royals fans should be looking at from Royals middle infielders in 2020, and how they can show whether these middle infielders will either break out or regress this upcoming season.


Adalberto Mondesi: 1.38 GB/FB ratio

Mondesi had a breakout campaign in 2018, as he posted a .276/.306/.498 slash with 14 home runs, 32 stolen bases, and a 114 wRC+ in 75 games and 291 plate appearances. After struggling to break-in at shortstop in Kansas City in previous years due to Alcides Escobar, manager Ned Yost gave him the reigns in the second half of 2018, and Mondesi showed signs that he could be come a superstar-esque player for the Royals in the mold of the Cubs’ Javy Baez, perhaps.

As expected, the Royals named Mondesi the starting shortstop on Opening Day in 2019. Unfortunately, the results were a bit mixed. Defensively and on the basepaths, Mondesi continued to be an elite player, as he posted a 13.3 Def rating, according to Fangraphs, and also stole 43 bases in 102 games. However, his offense regressed, as his homer total declined from 14 to 9 despite nearly 150 more plate appearances from 2018. Furthermore, his wRC+ dropped from 114 in 2018 to 82, and his strikeout rate increased from 26.5 percent to 29.8 from 2018 to 2019, respectively. While injuries certainly contributed to Mondesi’s regression (he only played in 102 games and was shut down due to shoulder issues which required him to get surgery), his contact issues and decline in power were concerning signs for the young, high-profile shortstop.

The biggest metric that could indicate whether or not Mondesi will find success is his GB/FB rate, which was 1.38 in 2019. The 24-year-old Dominican infielder put the ball in the air a lot more in 2018, as he not only posted a 1.10 GB/FB ratio, but also a 19.7 HR/FB rate and 43.1 hard hit rate. Those metrics explained Mondesi’s offensive breakout in 2018, and gave Royals fans hope that he could turn into an AL equivalent of Baez. However, in addition to his GB/FB ratio dropping, his HR/FB and hard hit rates also dropped to 9.3 and 37.8 percent, respectively. Thus, one can understand from those metrics that Mondesi putting the ball more on the ground ended up hurting his statistical line (and consequently, offensive production) in 2019.

Now that Mondesi is fully recovered from surgery (thanks to COVID extending the start of the season), it will be interesting to see if Mondesi can improve that GB/FB ratio and get it closer to that 2018 mark. If it is in the 1.10-1.20 range, then it is possible that we could see an offensive breakout from Mondesi which could match or surpass his 2018 in terms of impact. Mondesi has a lot of raw power, and that obviously showed two years ago. However, if Mondesi sees that rate fall in the 1.30-1.50 range, than it’s hard to imagine Mondesi being more than a slap-hitting threat in the Royals lineup. That’s not necessarily a bad thing of course, but at 24-years-old, it would nice to see Mondesi develop into something more, especially with his raw power tool.


Nicky Lopez: 0.35 BB/K ratio

A former 5th-round pick out of Creighton University in Omaha, Lopez has developed into a minor fan favorite of hardcore Royals fans. He was known for demonstrating solid plate discipline, good contact skills, and a dependable glove at either the shortstop or second base positions in the Minors. While he didn’t have any “elite” tools, his overall profile gave Royals fans hope that he could be a dependable option in the Royals middle infield for a good while.

Lopez made his Royals debut early in 2019, and unfortunately, it was a mixed bag. While his defense lived up to the hype, he struggled to adjust to Major League pitching after being called up from the Omaha Storm Chasers of the Pacific Coast League in May. In the first half of play in 48 games, Lopez hit .228 with a 0.33 BB.K ratio and 50 wRC+ in 203 plate appearances. However, in the second half, September especially, Lopez started to get comfortable and find his groove. In the last month of play, filling in for an injured Mondesi, Lopez hit .289 with a 1.00 BB/K ratio and 102 wRC+ over 48 plate appearances.

Lopez only posted a .084 ISO, which even for his standards was pretty low (he posted a .147 and .139 ISO in Omaha in 2019 and 2018, respectively). But at the end of the day, Lopez will never hit for much power at the Major League level. He’ll probably be a 5-10 home run guy at best, but as long as he can hit for contact and extend hits on the basepaths (which he can), then he will be a productive second baseman for the Royals not just in 2020, but beyond as well.

However, the 0.33 BB/K ratio was concerning, especially since plate discipline was Lopez’s calling card in the Minors. In 2019 in Omaha, Lopez posted an insane 4.00 BB/K ratio (highlighted by a K/9 rate of 3.6). In 2018 in Northwest Arkansas, he posted a 1.43 BB/K ratio. Usually, Lopez has started slow in his first exposure to a level (his BB/K ratio in NWA and Omaha debuts was 0.55 and 0.93, respectively). However, once he gets more at-bats, Lopez truly demonstrates one of the best batting eyes in the Royals organization. That was evident last year with the Royals, as his K/9 rate dropped from 16.7 percent in June to 12.0 to 10.5 to 6.3 from July to September, respectively. Thus, it’s not surprising that Lopez had his finest month as a Major League player during the last month of play.

The big issue will be not only how well Lopez improves his BB/K ratio, but how much? If Lopez can be in that 0.70 to 1.00 range, it’s possible that Lopez could perhaps extend his hot September of last year to a strong 60-game campaign in 2020. The Royals will need a productive Lopez at the plate to compete, and a productive Lopez will begin with how his batting eye, measurable through his BB/K ratio, transitions from that last month of 2019 to this season.


Erick Mejia: 14.3 percent swinging strike rate

Mejia may be the most intriguing beneficiary of the expanded rosters in 2020. During a normal season, Mejia, who was released from the 40-man roster this off-season, would probably be roster depth in Omaha, with only an outside chance of breaking in with the Major League club in Kansas City. However, with it being likely that there will be no Minor League season, and a 60-man roster that will include a 30-man taxi squad, Mejia’s chances of playing with the Royals this season suddenly look more likely.

Mejia was involved in the three-team trade with the White Sox and Dodgers that sent Scott Alexander to LA and Joakim Soria to Chicago in the Winter before the 2018 season. What makes Mejia intriguing is that he has multiple position value, as he can play all three outfield positions, and three infield positions (3B, SS, 2B) adequately. Furthermore, though Mejia doesn’t offer much power at the plate, he does offer some speed on the basepaths, as he stole 34 bases in Double-A Northwest Arkansas in 2018 and 19 bases in Omaha in 2019.

The big question with Mejia is whether or not he can hit enough to be a backup utility player at the Major League level. Unfortunately, he didn’t do much to impress the Royals in a September call up in 2019, as he hit .227 and posted a 67 wRC+ in nine games and 27 plate appearances with the Royals in 2019.

The key metric to observe for Mejia will be his swinging strike rate, which was 14.3 percent with the Royals a year ago. That percentage was pretty high in comparison to his Minor League rates, as he posted a swinging strike rate of 9.3 in Omaha in 2019 and 8.8 in Northwest Arkansas in 2018. If Mejia can decrease that swinging strike rate, that could benefit his other plate discipline metrics, which were pretty pedestrian. Mejia can have all kinds of utility and value on the basepaths, but it will be hard for him to find a roster spot with a contact rate of 71.2 percent. That percentage needs to be in the 75-77 percent range at the minimum for him to be a serious utility player.

It will be interesting to see if Mejia’s swinging strike percentage will regress in 2020. If he gets an opportunity and demonstrates better contact skills, it’s possible that he could find a role in a super backup role. If those swing-and-miss issues carry to 2020, it will be hard to see Mejia have much of a role on the Royals not only in 2020, but beyond as well.


Humberto Arteaga: 42.1 O-Swing percentage

Arteaga is a glove-first middle infielder whose value will be tied to his defense. Even in the Minors, Arteaga hasn’t flashed much of a bat, as he posted a wRC+ of 78 in 2019 and 85 in 2018 in Omaha the past two seasons. Hence, it’s hard to imagine Arteaga being much more than a glove-only backup for the Royals in 2020.

In his Major League debut last year, the now 26-year-old Arteaga didn’t demonstrate much at the plate, as he posted a .197/.258/230 slash and wRC+ of 30 in 41 games and 135 plate appearances. Unlike Mejia, who had a VERY brief cup of coffee with the Royals in 2019, Arteaga actually saw a little bit of playing time, and unfortunately for him, he didn’t do much to impress the Royals brass that he had much of a future at the Major League level with the organization (he and Mejia were both released from the 40-man this off-season). While he did garner an invite to Royals Spring Training this year, it seemed unlikely that he was going to make the Royals roster before COVID hit.

Much like Mejia, Arteaga benefits from an expanded roster, as the Royals lack middle infield options with Whit moving to the outfield, and no other options on the horizon in the Minors (Bobby Witt, Jr. is still a couple of years away at the soonest). While Arteaga doesn’t have Mejia’s speed or position utility, he may be a better defensive player, and he is better at making contact, as he posted a 78.8 contact rate last year, over 7 percent better than Mejia’s mark.

The big issue for Arteaga will be swinging out of the strike zone, as he posted a O-Swing percentage (percentage of pitches swung outside the strike zone) of 42.1 percent. The Major League average is 31.6 percent, so not only is Arteaga above that mark, but considerably so (10.5 percent to be specific). Arteaga actually flashes solid contact skills, and that may be the strongest tool of his offensive game. And thus, he has to develop better pitch recognition and chase at less stuff out of the strike zone if he wants to find a roster spot in Kansas City either this year or next.

Granted, that may be easier said than done, as Arteaga hasn’t posted a BB/K ratio over 0.38 at Double-A or above (BB/K ratio and plate discipline percentages correlate strongly). Therefore, Arteaga may just be a free swinger who can make better contact than most free swingers. However, if Arteaga can hone that plate discipline even just a little bit, it could go a long way in terms of him improving his case that he could be a solid, though unspectacular, backup infielder for the Royals in 2020.

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