Coming in to 2016 left field was one of the biggest question marks on the Reds roster. Marlon Byrd, the Reds opening day left fielder in 2015, had been traded to San Francisco at the deadline a season ago. Cincinnati's left fielder of the future Jesse Winker was an option, but ultimately was sent back down to the minors. Even late in spring training it was still unclear who would get the job. On March 31 C. Trent Rosecrans noted that Cincinnati had started eight players in left during the spring. Eventually the search zeroed in on two players: Adam Duvall and Scott Schebler. These names weren't splashy free agent signings or highly touted prospects. Understandably, Reds fans were skeptical about the production the team would get from this position.
However, one of the biggest question marks on the Reds roster coming in to 2016 has been one of its most pleasant surprises. Outside of Zack Cozart, who's offense has been a nice surprise itself, Adam Duvall has been the Reds most valuable position player by fWAR. So just how has one of the most unknown players on this roster become an important contributor?
Prior to 2016 Duvall had only spent a small amount of time at the major league level. In 2014 he played 28 games for the Giants, and last season the Reds called him up for 27 games. During his brief stint last season in Cincinnati he showed some promise at the plate given his 110 wRC+. He also showed the ability to play at least average defense in the outfield. These results led our own Cy Schourek to write this past March, "Duvall can do everything just enough to be interesting." This reality was hinted at during his brief stints in the majors, and it was fairly evident during his time in the Giants farm system.
So what has made Duvall so valuable to Cincinnati this season?
He's Making the Most of His Contact
When you first look at Duvall's offensive numbers it's easy to be underwhelmed. As of today he's hitting .241/.290/.466. That gives him a batting average and OBP currently below league average. It's that third number in Duvall's line that highlights what makes him valuable at the plate. His SLG% of .466 is above league average (.406), and it's good enough for fifteenth among left fielders (minimum of 50 PA). This shows us something about the value of Duvall's power this season, but SLG% isn't the best stat for measuring a player's pure power. For that we need a different metric.
This is probably a good point to have a quick discussion on SLG vs. ISO. Ben Humphrey of Viva El Birdo's actually had a helpful discussion on this in 2014 (I'll summarize his argument here). There are a few factors that make SLG an inferior stat to ISO in terms of measuring a players power. First, a hitter's singles are included when calculating their SLG%. This means that a player who hits for a high batting average can artificially inflate his SLG%, and it gives the impression that he was a better power hitter than he actually was. The other issue is that SLG% gives "arbitrary values" to different kinds of hits. It weighs a home run as four times more valuable than a single all of the time even though that's not always the case. ISO is a better measure of power specifically because it excludes singles from the rate. At its most basic level ISO is calculated by taking SLG - BA.
Duvall's value at hitting for extra bases becomes even clearer when you assess his ISO (isolated power). His current ISO of .224 is tenth best among left fielders this season, and is again well above league average (.163). It's fair to wish Duvall was making more contact (38.7 K%) or getting on base more (6.5 BB%, .290 OBP), but when he is making contact he's at least making the most of it. Even though he's currently having just below a league average offensive season (95 wRC+), he's been able to mitigate some of his deficiencies by hitting the ball hard.
He's Been a Great Defender
Prior to the season Billy Hamilton was pretty much the only sure thing in Cincinnati's outfield. Jay Bruce has been a good defender throughout his career, but defensive metrics have highlighted regression in his defense. No one was quite sure what to expect from Duvall in left. Prior to coming to Cincinnati he spent the bulk of his time at first and third in the minors for the Giants. It was only after arriving in Cincinnati that he started making the transition to the outfield.
Defensive metrics aren't perfect, and this early in the season it's tough to draw strong conclusions from the data. It's still worth noting that as of now these metrics value Duvall as a top five defensive left fielder. His 4 DRS trails only Starling Marte and Colby Rasmus. By UZR (3.3) he's been the best defensive left fielder in baseball. This biggest contributor to that number for Duvall is what is known as "range runs" (RngR). This stat tracks, "The number of runs above or below average a fielder is, determined by how the fielder is able to get to balls hit in his vicinity." According to this measure if there has been a ball hit in Duvall's vicinity, he's been one of the best in the game at getting to it.
It's easy to see some clear holes in Duvall's game. The rate at which he's striking out is too high, and it would be beneficial if he could take some more walks. Even with those deficiencies Duvall has found a way to contribute in a positive way to this Reds team. His ability to hit for extra bases is welcome and needed, and he's supplied well above average defense in left field so far. Ultimately this spot on the team will be Jesse Winker's, but while he's still developing in Louisville the Reds could do far worse than Duvall.