In 2015, Rosario played in 122 games for the Twins. He ended up being worth 2.3 fWAR, which ranked him 8th among American Leagued left fielders. If there was something Rosario was going to hang his hat on a season ago, it was his big league leading 15 triples, as well as his defensive prowess (16 assists 11 DRS). Unfortunately for Rosario, both of those areas are generally unrepeatable statistics.
Triples tend to be a by-product of happenstance. Of course speed is required to snag three bases in a single plate appearance, but a well placed base hit is generally a requirement as well. As far as outfield assists go, it's generally a fickle expectation to think a player will consistently put up gaudy numbers. In talking with Cold Omaha's Brandon Warne prior to the 2016 season, he surmised that assists were generally down slightly over time due likely to the fact that players aren't going to test a proven arm.
As could've been expected, Rosario has seen a dip in both categories that bolstered his performance a year ago. He has contributed just two triples over the course of 65 games, while contributing just five assists. In both instances, it appears that the expected regression did indeed take place.
Looking at Rosario though, the question has never been about whether or not he can hack it defensively or has speed. Instead, the concern has been whether or not his plate approach can hold up at the big league level. A free swinger that chases often and misses too much, it would need to be reigned in some to turn him into a big league regular.
So where are we when it comes to Rosario at the dish? Well, a season ago Rosario swung at pitches outside of the strike zone a ridiculous 45.6% percent of the time. He swung and missed 14.5% of the time and it equated to a .267/.289/.459 slash line. In 2016, he's chased 41.5% of the time while swinging and missing a heightened 16.1% of the time. Regardless, it's turned out to a near exact replica line of .269/.290/.438.
This season however, Rosario began with the big league club and was sent down after 32 games. Prior to his demotion, he was slashing a dismal .200/.218/.313 for Minnesota while chasing out of the zone 41.4% of the time and swinging through pitches nearly 20% of the time (19.6%). After going back to Rochester for both some refining and an attitude adjustment, he's returned to slash a very strong .331/.353/.551. When looking at his approach after heading back north, the chase rate remains high at 41.6% but his 13.1% swinging strike rate is the lowest it's been in his career.
So, what do we make of it all? Well, the reality is that a 40% chase rate isn't ideal in a vacuum, but Rosario is doing some things to make it work. First, he's improved his swing and miss ratio nearly 6% over the course of the season, and is now doing so less than at any point in his career. Rosario's contact percentage since rejoining the Twins is 76.2% which is also a career high. Then, if a guy is going to chase, you'd hope he puts the bat on the ball. When swinging at pitches out of the zone, Rosario is hitting them 70.7% of the time as opposed to a 64.5% mark over the course of his career.
In summarizing the situation, Eddie Rosario is not an ideal guy to model an at bat after. However, he's also made tweaks to his approach that allow him to take chances and benefit from them. He's a free swinger that has honed it in enough to make the process work. Expecting a guy like Rosario to hit near .300 at the highest level is probably always going to be a foolish bet. If he can make contact 75% of the time, swing and miss under 15% of the time, and barrel balls he chases at least 70% of the time, he should make things work.
Realistically, Rosario's approach and plate discipline is one that will take constant refining. He's never going to be able to not work at it, and that will have to be something the Twins impress on him. Committing to doing so though should continue to provide results that make him an above average player on a team that needs a host of them. Given what he's displayed this season, and what Minnesota has behind them, I'd pencil him into the future more quickly than I'd be looking to flip him.
Eddie Rosario does a lot of wrong things at the plate, but it seems as though he's put forth an effort to make them work for him, and right now it's paying dividends.
