August 16, 2017
Eddie Rosario, Reformed Hacker
Paul Molitor has always been a believer in Eddie Rosario’s swing. As a roving hitting instructor, Molitor worked with Rosario in the minors as far back as 2010, saying later that the left-handed hitter’s “ability to square up the ball” immediately caught his eye. Molitor replaced Ron Gardenhire as Twins manager in 2015, and during his first spring training at the helm he praised Rosario’s hitting ability on a daily basis. At the time Rosario was 23 years old and coming off a disappointing Double-A season in which he hit just .243/.286/.387 and was suspended 50 games for marijuana use, but Molitor believed.
Early that May the Twins needed outfield reinforcements and at Molitor’s urging they bypassed Aaron Hicks to call up Rosario, who was hitting just .242/.280/.379 with a 17/5 K/BB ratio in 23 games at Triple-A. For all the talk about his upside, Rosario had a sub-.700 OPS above Single-A for his career and it had been around 18 months since he was a productive hitter at any level, but as Molitor explained: “I wanted to give Eddie an opportunity to get up here. I’ve been around him enough to know that for that kid, it’s just been a matter of him learning to apply himself a little bit more consistently, and I think he’s been doing that.”
It turns out, Molitor was half right. Even as a 23-year-old rushed to the big leagues despite very little high-minors success, Rosario’s natural hitting ability allowed him to bat .267 with 13 homers, 46 total extra-base hits, and a .467 slugging percentage in 122 games as a rookie (including, fittingly, a homer on the very first pitch he saw). The kid could definitely hit, against righties and lefties, but what Rosario couldn’t do was avoid swinging at everything. He struck out 118 times, drew just 15 unintentional walks, and swung at an MLB-high 47 percent of pitches outside the strike zone while posting a .289 on-base percentage.
Rosario’s non-existent plate discipline was anything but a surprise based on his minor-league track record and it continued last season, with a 91/12 K/BB ratio, .295 on-base percentage, and MLB’s fourth-highest out-of-zone swing rate. He still managed to hit .269 and slug .421, including a second-half hot streak after a brief midseason demotion to Triple-A, but even for Molitor it was getting harder not to worry that Rosario’s flaws—lack of plate discipline, but also declining defense, baserunning mistakes, and the absence of the aforementioned consistency—would hold him back from becoming an impact hitter.
Here are the highest out-of-zone swing rates from 2015-2016, with a minimum of 500 plate appearances:
This season looked likely to be the same frustrating story for Rosario when he hit just .248/.273/.380 with a 28/5 K/BB ratio through 40 games, once again swinging at more than 44 percent of pitches outside the strike zone. Except it wasn’t the same story. Three seasons and 1,000 plate appearances into his career, at age 25 and with more demotion talk swirling, he finally hacked his way out of the swing-at-everything forrest. He’s still far from a patient hitter and falling back into bad habits wouldn’t shock anyone, but he’s made major in-season strides when it comes to laying off pitches outside the strike zone:
Twins fans who see that August chase rate creeping back up a little bit have every reason to cringe, and sure enough over the weekend Rosario did strike out swinging at a pitch that nearly hit him in the head. Molitor has shown signs of heavy skepticism himself, batting Rosario higher than sixth in the Twins’ lineup just 16 times all year, and just once higher than fifth. However, my main takeaway is that for two-and-a-half months Rosario has maintained a 35-38 percent swing rate on out-of-zone pitches after two-and-a-half seasons of being in the mid-40s.
He’s gone from being the biggest hacker in baseball to simply being a run-of-the-mill hacker, which is an important step and one that many people were starting to doubt he’d ever take. Rosario already has more unintentional walks (23) in 398 plate appearances this year than he totaled (22) in 828 plate appearances during his first two seasons, and 20 of this year’s 23 walks have come since late May. He has a walk rate of 7.8 percent during that 67-game span, compared to 2.8 percent in his career up to that point, and he’s in danger of looking downright patient at times against right-handed pitchers.
Whether it’s the chicken or the egg, Rosario has been absolutely crushing the ball throughout his (relative) walk-fest, hitting .321/.371/.568 with 13 homers, 19 doubles, and a very reasonable 48/20 K/BB ratio. His average exit velocity has risen from 84.9 mph in April and May to 87.1 mph since June 1, including 89.0 mph so far in August. His newfound patience has forced pitchers to throw him more strikes—49 percent since June 1 after being 44-46 percent in 2015, 2016, and the first two months of 2017—and when they do he’s used that sweet swing to inflict damage.
And it’s not just Rosario, although he’s certainly taken the most prominent step forward under first-year hitting coach James Rowson. Minnesota has the youngest lineup in the American League, with Rosario among their five 25-and-under regulars, yet the Twins have the league’s second-highest walk rate and fifth-highest on-base percentage. After swinging at 31 percent of pitches outside the strike zone as a team in both 2015 and 2016, they’ve chased 28 percent this year for the league’s second-best mark. It’s still not a top lineup, but thanks in large part to Rosario they’re getting closer.
Rosario is finally making pitchers throw him strikes, rather than hacking at whatever slop they choose to give him, and in the process he’s allowing the natural hitting talent that Molitor was once so smitten with to shine through in a huge way. He’s addressed his most glaring weakness, improving it from horrendous to merely poor, and unlocked the impact bat that Molitor and the Twins have been waiting for since 2015. Now it’s on Rosario, Molitor, and Rowson to avoid falling back into his bad habits, because for as much as he’s thriving right now, if the plate discipline leaves the whole party shuts down.