One of the more surprising All Star selections was the one of Cincinnati Reds left fielder Adam Duvall. Duvall was acquired from the Giants along with minor league pitcher Keury Mella (who was arguably considered the main piece of the trade at the time) in the Mike Leake deal. After his surprising pick to the All Star Team, and his good performance in the Home Run Derby, people are starting to take notice.

I spoke of this topic on the Banished to the Pen podcast recently, but while Duvall is a classic one-tool player, what a tool it’s been so far in the current season. Duvall is slugging .551, which is good for 9th in the National League. That’s the good. However, the on-base percentage is a disappointing .288. If one is slugging .551 then an OBP of .288 is OK, not optimal, but fine. The problem is, you pretty much have to maintain that .550ish SLG to continue being a productive player. If you are a one dimensional player, and that main tool declines, you’re in trouble. Going to the Baseball Reference Play Index, you can see here that in the expansion era (since 1961), not one player has ever maintained a .550 SLG with under a .300 OBP over a full season. Duvall’s 2016 is the only season that shows up in the report. If you lower the SLG requirement to .500, you get something looking like this:

Provided by Baseball-Reference.com

So, three times ever, not counting Duvall’s current season. Mike Jacobs was a sub-replacement player, Tony Armas and Dave Kingman were both good players, but still, they only did that one time each. Armas only slugged .500 or more three times, and Kingman actually had a .302 career OBP, so he did have some decent on-base ability for a guy with a career .236 AVG. What this says to me is that it isn’t likely that Duvall can continue to carry such a high SLG without increasing his OBP, which he could do. But while he did walk at a decent clip in A ball, as he went higher up the ladder his walk rate slowly decreased, until now as a major leaguer to 5.3% (granted it’s only 473 plate appearances). So, let’s assume that Duvall isn’t going to become an on-base wizard at the age of 27, and based on previous history, that his slugging will not stay over .500. Let’s go back to the Play Index (using Sam Miller’s favorite starting year of 1988 for no particular reason) and sort by Wins Above Average, so we can see how likely it is for a player to be an average or better player with an OBP of less than .300, and let’s set it to weed out the players who provide most of their value defensively, so set Defensive Runs at 9 or less.



Provided by Baseball-Reference.com

So, basically, to be an average or better player with a sub .300 OBP, you either have to be a fairly good fielder at a premium fielding position (lots of shortstops and catchers in that above list) or have a year where you slug enough to offset the negative on-base value, but guys like Pedro Alvarez and Melvin Upton aren’t exactly bastions of consistency. Now, Duvall is currently +11 DRS (as well as +5 UZR and +11 FRAA), but we know the pitfalls of small sample defensive metrics, so I can’t say whether Duvall is a plus defender or not.

In conclusion, given the fact that this is Adam Duvall’s age 27 season, and all the evidence to the contrary that this current season is nothing but an outlier, this is likely Duvall’s career year. So if I were running the Cincinnati Reds, I’d have “SELL HIGH” running through my head right now.