The Cardinals missed out on Giancarlo Stanton in December, quickly pivoted to the other Marlins outfielders, Marcell Ozuna and Christian Yelich, and soon - as we're all aware - landed on Ozuna. It was a good deal for this Cardinals team who can use Ozuna's potent bat in and around that clean-up spot, and because he comes with only two years of team-control (unlike Yelich), he was a rather inexpensive acquisition. We (ideally) get to watch Ozuna hit doubles and home runs for at least a few years, and Alex Reyes, Luke Weaver, Jack Flaherty, et al, are still Cardinals. Hard to not like that.
However, Yelich does bring things to the table that Ozuna does not. There's that already alluded to "several more years of team control" thing, but there's another thing, and it's that Yelich bats from the left side, and it probably wouldn't kill the Cardinals to have another player who can do that. Looking at the 40-man roster as it currently stands, the Cardinals have five position players who can hit from the left side: Matt Carpenter, Dexter Fowler (switch), Kolten Wong, Greg Garcia, and Breyvic Valera (switch). All are infielders with the exception of Fowler.
Why does this matter? It probably doesn't matter all that much. But for sport, let's say it does. Well, the Cardinals had the fewest number of plate appearances (1,847) in the National League in 2017 from the left side, and with easily a majority of pitchers in Major League Baseball throwing right, the Cardinals are gaining the advantage of the platoon less often than their competition.
Here are all National League teams in 2017, as sorted by plate appearances with the platoon advantage, whether facing lefties or righties:
Plate appearances with the platoon advantage (2017)
The Cardinals only had 2,565 plate appearances in 2017 with the platoon advantage - the lowest in the NL, as shown above - with 328 plate appearances separating them from the Pirates, who had the second fewest. The next largest difference from one team to the next is between the Cubs and Dodgers, who are separated by 204 plate appearances.
From the common sense approach that players typically hit better with a platoon advantage (it's called an "advantage," after all), Cardinals hitters in 2017 absolutely capitalized in these situations when compared to their peers. They just had less opportunity. Here's how NL teams fared by wRC+ with the platoon advantage against righties, as sorted by plate appearances which are measured on the right (my graphs are still bad).
Platoon advantage versus righties (2017)
The Cardinals had the fewest plate appearances (1,562) when gifted the platoon against righties, which is to be expected since, per above, they had the fewest overall. But look at what they did in those opportunities - a 117 wRC+, highest in the league. That was a lot of Carpenter and Fowler, who combined for a 132 wRC+ in 856 plate appearances against righties.
Against lefties, basically the same thing:
Platoon advantage versus lefties (2017)
Here, the Cardinals had the sixth fewest plate appearances in the NL with the platoon advantage against lefties, with a 111 wRC+ in those situations - second best in the league behind the Dodgers (112). Most notably, they are the only team in the bottom six by plate appearances when platooning against both righties and lefties.
Again, I don't think this is a huge deal, and Rob Mains of Baseball Prospectus has noted that platooning is down not just in St. Louis but all across the league. Obviously, you never sacrifice a good hitter for the sake of a platoon advantage so this is not to advocate for a larger role for Greg Garcia. And none of this is to say the 2018 lineup shouldn't be good. Quite the contrary.
I also don't have much in the way of a thrilling conclusion for how the Cardinals can fix this problem (to whatever extent you want to call it a problem) in 2018. The lineup, 1-8, is righty-centric like last season. The starting pitchers, like last season, are all righties, too, and they took the second most plate appearances for pitchers batting from the right side in the NL in 2017 behind the Nationals. So right there, maybe that's how they can address one big problem, and one much smaller problem: Pull the starting pitchers earlier, and give some of their at-bats to whatever lefty might be on the bench. It's not much but it's something.
FanGraphs Splits Leaderboards was a great resource for this post.
Photo credit: Jeff Niehaus