In acquiring Dexter Fowler, the Cardinals poised themselves to improve their outfield defense in two ways: Fowler - while there is some question about his numbers - is expected to be a slight upgrade over Randal Grichuk as a defender in center. But the acquisition also moves Grichuk into left field, where he is expected to be a significant upgrade over Matt Holliday.
Late-career Holliday’s defensive limitations are well-known, so it won’t be a surprise if Grichuk achieves “better than Holliday” levels of defense. But there’s also a widely held perception that any player who is able to play center - even at an average-ish level - will be an excellent corner defender. Will that hold true for Grichuk?
One of the more recent bits of data to spill out of the Statcast treasure trove has to do with outfield defense. Over at Baseball Savant, you can now see several defensive charts for center fielders. Fly balls are divided into 0-5 star plays, based on how likely they are to be made. The differences between Grichuk and Fowler are pretty striking.
In a nutshell, Fowler makes all of the routine plays, but very few 4-5 star plays. Grichuk does make a few highlight-reel plays, but also misses several very easy, 0-1 star plays.
There are a variety of charts you can see over at Baseball Savant, but I thought these plots of the two players Base Hits Allowed were perhaps most telling:
While Fowler and Grichuk’s defensive value may grade out similarly (in CF), they way they go about compiling that value is quite different.
Fowler’s range is probably smaller, but he is extremely consistent within his range. That would seem to lend further credence to the narrative that his overall defensive value was greatly improved by better positioning, and specifically having him play deeper.
Switching over to Inside Edge fielding data at Fangraphs, for his career, Fowler made 99% of his routine plays and 86% of his likely plays. Grichuk has made just 64% of plays within the likely range, though his percentages are better than Fowler as you push out into the more unlikely plays.
Grichuk will certainly give the Cardinals more range in left field, but his occasional inconsistency on routine balls will come with him as well. As a result, while I could certainly see him performing slightly above-average as a left fielder, I wouldn’t expect elite defense.