Going into the winter warm up, the Cardinals had, arguably, the best fourth outfielder in the entire league. Randal Grichuk was the most productive fourth outfielder per 600 PA, projected for 1.9 WAR. Last week, he was traded to the Blue Jays for Dominic Leone and Connor Greene, welcome additions to the pitching staff. However, with Grichuk gone, the depth chart shifts slightly.
As a result of the trade, Harrison Bader will probably start the season in St. Louis instead of Memphis and Jose Martinez becomes the new fourth outfielder. He is, of course, not only a fourth outfielder—he provides additional value. He can play first base, as the Cardinals have used him in the past. With his bat in the lineup, Matheny can shift Matt Carpenter to third base in order to rest Jedd Gyorko, or simply give Carpenter the day off. Essentially, Martinez adds a nice flexibility to the roster, providing both infield and outfield depth.
Still, even if only evaluated as an outfielder, Martinez, who started the offseason as a 5th outfielder, is a valuable asset.
If we use Depth Charts projections for 2018, there are some noticeable data points from past and present Cardinals. Unsurprisingly, Marcell Ozuna is projected to be the 8th most productive outfielder. Tommy Pham is similarly projected to be elite, performing at the 16th highest rate. On the other end, despite being projected for 357 plate appearances, Magneuris Sierra projects for a league worst -0.6 WAR and a bottom 10 finish in WAR per 600 plate appearances: -1.0.
Jose Martinez is projected for a 0.6 WAR season in 2018. As a backup outfielder, that number can be a little misleading, considering he is slotted for just over 200 plate appearances. Although his 0.6 WAR number places him in a tie for 6th with Denard Span of the Rays for most productive fourth outfielder in the league, his WAR per 600 plate appearances number gives a more accurate insight into his true value.
Jose Martinez is projected for 1.8 WAR per 600 PA. That number is just a tenth of a point below Grichuk’s projection, when he was a fourth outfielder for the Cardinals just a week ago, and still good for 1st in all of baseball among fourth outfielders.
Visibly, there is a very clear upper echelon of 4th outfielders—Jose Martinez, Matt Joyce, Brett Gardner, and Albert Almora Jr. all separate themselves from the pack. Martinez and Gardner join this list in large part due to significant offseason moves by their respective teams: the Cardinals acquired Ozuna and the Yankees added Stanton. Joyce and Almora Jr. are at the top of this list in large part due to a lack of a clear cut starting outfield. Matt Joyce is one of six Oakland Athletic outfielders projected for over 400 plate appearances. Likewise, Almora Jr. is one of five Chicago Cub players projected for over 400 plate appearances.
The Cardinals not only have a clear cut starting outfield, but also a player in Martinez who projects as the most valuable fourth outfielder in the league. Period.
This data also helps us make sense of the Grichuk trade. Although Randal Grichuk certainly has the skills to carry an offense at times, he was not in a position to play everyday in St. Louis. With his trade to the Blue Jays, the Cardinals solidified their bullpen and are left with a fourth outfielder who still projects as the most valuable player among his peers.