Whit Merrifield has been, by far, the best 29-year old in baseball this season

Whit Merrifield has posted 4.5 fWAR in 2018 as a 29-year old. The next closest 29-year old to Whit in terms of fWAR is Pittsburgh’s Starling Marte, with 3.1. One question that I find myself asking on a regular basis is, “Can Whit Merrifield sustain this kind of success moving forward?” It’s a fair question and I think plenty of folks have tried to answer it in one way or another.

The importance of Whit Merrifield sustaining success past his age-29 season, in which he’s been worth 4.5 fWAR through 147 games, can not be understated for the future of the Kansas City Royals. The Royals have a few options when it comes to handling Whit this off-season, and they’ll need him to show continued success for each of them:

1. Extend Whit Merrifield if you think he’s part of the next core (I hate this idea)
2. Do nothing (this probably means he’s traded next summer when Nicky Lopez is ready to play in the big leagues every day)
3. Trade him (love it)

In the first two scenarios, the Royals will need Merrifield to be equally, if not more, successful than he has been in 2019. Dayton Moore and company will either put faith in him to be an All-Star in 2022, or at least be good enough for four months to begin 2019 that he doesn’t lose trade value between now and then.

That’s why I’m on the side of trading Whit Merrifield this off-season. I went back to 2013 and tracked the production of every 29-year old to be worth as many wins (FanGraphs) as Whit in 2018, and compared it with their performance in their age 30 season. Here is some of what I found:

• There have been 19 29-year olds to post at least 4.5 fWAR since 2013 (including Whit)
• Of the 18 players to play in their age 30 season, only 5 posted 4.5+ fWAR again (27.8%)
• Of the five players to post 4.5+ fWAR again in their age 30 season: one posted the exact same fWAR, two improved slightly, and two decreased slightly
• The average change in fWAR for these five players between age 29 and 30 was 0.06
• Of the five players to post 4.5+ fWAR again in their age 30 season: four of the five saw an increase in wRC+, with an average increase of 5.6 points
• Of the five players to post 4.5+ fWAR again in their age 30 season: four of the five saw an increase in their BB%, with an average increase of 2.6%
• Of the five players to post 4.5+ fWAR again in their age 30 season: two saw an increase in K%, two saw a decrease in K%, and one remained even; good for an average increase of 0.58%
• Of the 13 players to post less than 4.5 fWAR in their age 30 season, injury played a significant role for 10 of them (76.9%)

So, is it possible for Whit Merrifield to hold his current playing level? Actually...yeah. Whit Merrifield has been really healthy throughout his career. He’s nearly doubled his BB% from last year and his K% has remained steady after dropping over 7% from his debut season in 2016. His wRC+ (118) has improved 13 points from 2017 (105), which was 14 points better than in 2016 (91).

The handling of Whit Merrifield will be a franchise altering decision this off-season. It ought to be the top priority of the Royals front office and every decision they make should be based on whether or not Whit Merrifield is going to be around in 2019. He has been a top 25 position player in all of baseball this season, and the Royals need to plan the future around him. Regardless of whether that means he is traded, or on the Opening Day roster.