Many suspected that Raúl Mondesí was probably not ready to be an every-day major-league baseball player on Opening Day. This did not keep the Royals from staying with their organizational philosophy that extended time in AAA is not needed and that development can occur instead at the Major League level. Predictably, Mondesi floundered with a .161 wOBA, which translates to a wRC+ of -12. He struck out in nearly 35% of his plate appearances and was clearly overmatched, often feebly flailing at offerings nowhere in the vicinity of the strike zone.
It has been nearly a month since Mondesí was demoted to Omaha, and on the face of it, he is performing well, hitting .324/.387/.574 in his first 17 games. However, it would be a mistake to rush him back to the big leagues at this point. First, Whit Merrifield has been adequate for the Royals at second base and replacing him with Mondesí would almost certainly result in a net negative in value for the team. Second, while a recent hot streak has provided Mondesí with shiny offensive numbers, the underlying statistics indicate he still has work ahead before those numbers translate to major league success.
Whit Merrifield is far from setting the world on fire, but his offense has been non-atrocious (wRC+ of 85) and early returns from defensive metrics have given him positive value. In fact, (small sample size alert) Merrifield is tied for third among second basemen in the MLB in defensive runs saved (4) in 100 less innings than the AL leader (Ian Kinsler - 6) and half the innings of the NL leader (DJ LeMahieu - 6). The result is a rWAR for ‘two-bit’ Whit that is equal to Salvador Perez (0.9) and an fWAR (0.5) just shy of Mike Moustakas (0.6). No rational human being would compare Whit to either of those players, the point being he is providing positive value for the Royals.
While Whit's defensive numbers seem due for some regression, his offense should also meander towards league-average. He has increased his walk rate slightly over last year (6.2% this year vs. 5.7% last year) and reduced his strikeout rate from 21.7% to 16.5%. It would be surprising to see Merrifield be league-average over a full season with the bat, but it is well within reason to believe he should be closer to 10% below league average (90 wRC+) than his current standing of 15% below (85 wRC+).
ZIPS projects him to be worth 0.7 WAR the rest of the season, which would make him a 1.2 WAR player after posting 1.6 rWAR and 1.7fWAR in 2016. Conversely, if Mondesí maintained his year-to-date career major league offensive pace, he would essentially need to post all-time MLB records in both defensive AND base-running metrics just to accumulate 1 WAR.
Mondesí has made some notable strides since he was demoted to AAA. In 61 plate appearances in 2016 he posted a walk rate of 3.3% and a strikeout rate of 31.1%. In 2017 those have improved to 9.3% and 24% respectively in 77 plate appearances. These numbers are more predictive of future success than the BABIP driven numbers he has put up in his two previous short AAA stints. In 2016 he had a BABIP of .444 and wRC+ of 123, in 2017 his BABIP is .395 with a wRC+ of 121.
The underlying numbers indicate his performance at AAA is likely not representative of his true talent level and it should not be expected that he would maintain this pace moving forward. A look at his batted ball profile also backs up this assumption as his line drive rate (18.2%) is his lowest since he was in A+ and his ground ball rate (52.3%) is by far the highest it has been his entire career. It would be a mistake to take his offensive production at face value and assume it is indicative of a player ready to face major league pitching.
In conclusion, although Raul Mondesí has made noticeable improvements in his offensive profile, he still would benefit from additional time in AAA. Whit Merrifield has been more cromulent than a look at his triple slash (.230/.292/.402) would indicate and Mondesí is likely not performing as well as his minor league numbers show. As a result, it would be a mistake for Royals officials to be seduced by Mondesí’s recent Omaha success and return him to the big league club.