The Chicago Cubs are pinning their future on the improvement of Starlin Castro. Three years into his career, Castro has been a slightly above-average player. His 103 wRC+ confirms that notion, and his .330 career wOBA is hardly elite. But there is reason for optimism. Castro is just 23-years-old, and has been a regular in the majors since his age-20 season. While his offensive performance hasn’t been great thus far, there’s reason to believe he can turn into a great hitter.
There’s something to be said about Castro’s 1912 plate appearances before his age-23 season. Very few hitters come up that early in their careers and hold their own. While the offensive performance hasn’t been great, it’s put him among a pretty desirable group of players.
A couple things stand out in that chart. Some of the hitters on that list turned into great players. Any list featuring Roberto Alomar, Adrian Beltre and George Brett, to name a few, is incredibly promising. On top of that, Castro has more plate appearances than every every player but Alomar.
A fair amount of these players improved at age-23. Of the 21 players in the sample, eight saw a decline in their numbers the following season, and two players remained at the same offensive level. Eleven players saw their wOBA improve. Based on this list, there’s a 62% chance Castro either remains at the same level, or sees significant improvement in his numbers this season.
There are some problems with that list, however. Jose Canseco and Tim Raines may have produced a similar offensive wOBA at the same age, but were radically different hitters than Castro. Castro doesn’t have great plate discipline, and relies on high-contact rates at the plate. Though the power has improved, Castro hasn’t displayed strong slugging percentages yet.
Let’s take the same list, and find players who utilized the same approach at the plate. This will reduce the sample we’re working from, but will provide more similar players. Doing so gives us new list of eight players, including Castro. Now, let’s look at how these players performed during their age-23 season.
There are still some really good hitters on that list, including Brett, Paul Molitor and Ivan Rodriguez. Castro’s strikeout rate has been pretty consistent over his career, so Brett, Molitor and Gregg Jefferies are slightly worse comps on the list. The rest of the players posted nearly identical strikeout and walk rates.
Though the sample is small, there’s reason to believe Castro will see an offensive jump this season. Jefferies and Carney Lansford saw their performance decline. In Lansford’s case, he was hurt by poor luck on batted balls. Pudge’s offensive levels stayed the same, but he took a step forward the following year. The other four players on the list took significant steps forward. Ruben Sierra led the pack with a .391 wOBA, and slugged 29 home runs. That type of power isn’t something Castro has shown in his career, so we probably shouldn’t expect a similar outburst. Brett and Molitor were already slightly better than Castro at the plate, so their performances represent what he would do if he cut down on his strikeouts, which doesn’t seem likely given his consistency in that area. Garry Templeton is interesting. He walked even less than Castro, but relied on a high-contact approach and managed to improve his wOBA. Some of that was inflated by a high .351 BABIP, though.
Given the players on that second list, Castro should maintain his current level of offensive performance at the very least. There’s a chance he sees a small step forward, like Rodriguez and Templeton. It’s less likely that he sees a huge breakout unless his skills have changed.
Even if he doesn’t take a step forward this season, Castro is still on a strong path. A fair amount of his comps turned into future stars. Castro’s age is a big reason to remain optimistic. The players who handle the majors at age-20 typically turn into pretty great contributors. It might take some time, but Castro is well on his way to becoming the franchise player the Cubs need.