Santana's Breakout Success in 2014 is Unsustainable in 2015
Danny Santana was a pleasant surprise last season for the Minnesota Twins and fantasy owners alike. He was called up from the minors in May and posted a .319/.353/.472 line in 430 plate appearances, with seven HR and 20 SB. Add it all up, and he was one of the best shortstops in both real and fake baseball-- his .362 wOBA tied with Hanley Ramirez for best at the position.
That's not going to happen again.
Santana's success last season was fueled in no small way by an absurd .405 batting average on balls in play (BABIP). Granted, he's got the speed to support a higher-than-average mark, and a 26% line drive rate shows he was hitting the ball with plenty of authority. Still, his previous best in the minors was a much more reasonable .353. In the last 10 years, the only qualified hitter to post a BABIP over .400 was Joey Votto in 2012. Votto is a preternaturally gifted hitter who pops up about once every two seasons... and his BABIP still fell 44 points in the following season. We know that hitters have some degree of control over their BABIP, but virtually nobody is capable of sustaining the heights Santana achieved in 2014.
Also working against Santana are his middling plate discipline metrics. He's an aggressive hitter, which leads to a strikeout rate more in line with a slugger's than that of a slap-hitting middle infielder. He walked only 4.4% of the time last season, and his best showing in the minors was just 6.1%. Santana's value takes a huge hit if he isn't able to maintain a high batting average, and that should make you leery.
Santana does have a few things going for him. The power he showed last season wasn't too far out of line with his prior performance, and he's only 24 years old. He also has 30-SB upside, if he can stay healthy and hit well enough to stay in the lineup. Only a dozen players reached that mark a year ago, and somehow only two were shortstops. The position truly is a wasteland for fantasy purposes-- a mere 10 players were league-average hitters according to wRC+. Santana was one of them, and he has some room to decline precipitously and still be able to make that claim. In the current depressed offensive environment, an average bat with top-end speed is worth rostering.
The less analytically inclined, however, will almost certainly take Santana too early or pay too much for his services. And however you feel about positional scarcity, it's important to remember that value should trump all else. It's tough to imagine Santana providing a good return on your investment in 2015.
In Summary
Unsustainable batted-ball luck carried Santana to a breakout season; owners should exercise caution and restraint when bidding for him in 2015. That said, he brings enough to the table at a weak position that he's likely worth a spot on your roster, if you can avoid the career-year tax.