It's no great stretch to claim that Wilin Rosario is one of the most intriguing players on the Colorado Rockies' roster. He arguably has the most raw power of any other player in the organization, as evidenced by his 28 homer rookie season in 2012. When you launch nearly 30 dingers in only 426 plate appearances, opposing teams are going to start looking for weaknesses. In the early going of 2013, it appears that the scouting report on Wilin is just two words long: No fastballs.
Among Major League baseball players with at least 40 plate appearances, Rosario has seen the fewest fastballs of anyone. His 38.4 Fastball% is a full four percentage points lower than Josh Hamilton's, and Hamilton has been known to swing at everything he looks at, including low flying aircraft. And yet he sees more straight fastballs than Wilin.
Those fastballs have been replaced by off-speed breaking balls. Rosario has seen sliders 30.6 percent of the time, a number that leads the league by a fair margin. Accordingly, he sees pitches in the strike zone only 39.8% of the time, the 17th lowest number in the league. Pitchers want to get him to chase.
Has he obliged? According to Fangraphs, his swing percentage at pitches outside the strike zone is 35.5%, which is 41st in the league. Mashers like Ryan Braun, Adam Jones, Pablo Sandoval, Bryce Harper, Miguel Cabrera, and Hamilton (obviously) have all swung at more pitches out of the zone than Rosario. So he has demonstrated some ability to spit on the sliders.
However, that ability has not yet translated to his walk rate, which sits at a paltry 3.6%. He sees plenty of pitches per at bat; nearly four per plate appearance, which has him 52nd in the league, above the average. So while he has some discipline, and he works some deep counts, most of his at bats either end with him putting the ball in play or striking out. Of course, putting it in play has worked out pretty well so far this year; his triple slash line (AVG/OBP/SLG) is a healthy .302/.327/.547, good for a 126 wRC+.
The question is whether that's a sustainable approach. His batting average on balls put in play is .353, a number that only elite contact and speed guys can maintain. Wilin does not fall in that category. His current 2013 numbers actually look quite a bit like his 2012, except with a little luck with hits falling in; a more normalized BABIP probably puts him near where he was last year (.270/.312/.530). That's an above average line, especially for a catcher.
But when I look at his power to all fields, I end up dreaming that there could be more there. If he develops just a bit more patience, perhaps his walk rate will spike. If he demonstrates the ability to walk, maybe pitchers will have no choice but to throw him more fastballs. And if they throw him more fastballs, Wilin will hit the ball a really long way. It seems eminently possible, and he is only 24. There is a solid chance that Rosario's offense makes the jump from above average to elite. Should he do so, the Rockies' lineup could end up being the most fearsome in the Majors.