Greenville pitching coach Walter Miranda has been coaching in the Minor Leagues for 16 years, and he's never tutored a 19-year-old quite like Michael Kopech.
A 2014 first-round pick (33rd overall), Kopech was obviously well thought of coming out of high school. MLB.com ranked him 44th in the 2014 Draft class, noting his fastball sat in the low 90s and had hit 97 mph. There were questions about his secondary pitches and his delivery, so big velocity was clearly his calling card.
Boston may have expected Kopech to add velocity, but odds are they didn't expect so much heat so quickly. As a 19-year-old with the Class A Drive, the 6-foot-3 right-hander has hit 100 mph a few times this year and routinely sits in the upper 90s throughout his starts.
"It's the first time I've had a guy with that type of ability," Miranda said. "He's a guy that goes from the first inning and still pitches in the fifth inning, still throwing in the upper 90s."
That kind of consistent velocity is rare in any hurler, but it's especially uncommon for a teenager in his first full Minor League season. Miranda ties the extra smoke to two factors.
For one, Kopech draws rave reviews for his makeup and has worked tirelessly with Boston's strength and conditioning coaches. Miranda says he sees a notable difference in Kopech's overall strength since last year.
Second, Boston has overhauled Kopech's mechanics, making some dramatic changes to help the right-hander repeat his delivery.
As a high-schooler, Kopech began throwing by rocking his left foot at least a foot to the left of the rubber and sliding his right foot onto the extreme first-base side of the mound. He'd lift his leg theatrically from there, bringing his left knee all the way to his left shoulder, tucking his left arm between his thigh and his chest.
He'd then enter into a deep drop-and-drive motion, leaning his body back toward the second baseman before making his move toward the plate.
As a pro, he's ditched the excessive first movement and lowered the leg kick. Most notably, he's cut the drop-and-drive from his delivery, keeping a firmer back side and staying taller through his entire motion.
You can see the differences in the screengrabs below. The first is taken from Kopech's appearance at the Perfect Game All-American Classic in San Diego on Aug. 11, 2013 -- his mechanics looked largely the same in his senior year at Mount Pleasant High School in Texas. The latter image is taken from Kopech's May 22 start for Greenville, which you can watch on MiLB.TV.
"The first thing we started working on was his foundation," Miranda said. "The lower half of his body, it had a lot of movement. We quieted down that leg kick -- that's the main thing. As soon as he started working and started feeling that, you could see the results getting better, him being more consistent.
"He was over-rotating, had the real high leg kick and finished to the first-base side. Now, we've worked on his direction, and everything starts with the lower half of the body. We quieted that down, and now he's working over the rubber and has better direction."
The mechanical adjustments have helped Kopech improve his command. He's walked just nine batters in 28 2/3 innings with the Drive -- this after walking nine in 13 2/3 innings in the Gulf Coast League last year. He's racking up the strikeouts, too, punching out 30 while posting a 2.83 ERA in seven starts.
Miranda thinks Kopech's curve has improved, as well. Kopech came to Boston with a slider that Miranda said was sometimes "slurvey" and lacked consistent bite. With his new delivery, Kopech has instead turned to a power curveball that Miranda thinks has big upside. He may pick the slider back up at some point, but the curve has become his primary breaking ball for now.
"Now, it's still a slurve at times, but more often it's more like a curve, a power curveball," Miranda said. "He gets a lot of spin on the ball. It has late bite. When everything is in place -- mechanically is in place -- it's pretty good."
Kopech never had to throw a changeup in high school, so the pitch lags behind his fastball and breaking ball for now. Boston has him working it into his repertoire, and now that he's doing a better job repeating his delivery, Kopech will focus on improving the slow ball.
The velocity and breaking ball should be enough to get Kopech to the Majors if he can stay healthy. He'll need a third pitch if he's going to start, and Boston thinks it could be the changeup. Until then, he won't run into many Class A hitters who can punish his 100 mph fastballs.
"He's an extraordinary talent," Miranda said. "He's very strong, works hard. He works with a purpose. He knows what he needs to do to get better. He knows he needs to put in the effort to get better. That's what he's doing."
Twins 3B Miguel Sano, Double-A Chattanooga: Miguel Sano in April: .159 average, .684 OPS, six extra-base hits. Miguel Sano in May: .311 average, .970 OPS, 14 extra-base hits. At this point, it's safe to assume the 22-year-old has shaken the rust accrued after he missed the entire 2014 season following Tommy John surgery. Now, the powerful third baseman has to prove he can repeat those May results consistently at the Double-A level. Sano struck out in 29 percent of his at-bats at Double-A in 2013, and that whiff rate was something Minnesota wanted him to improve this year. He's posted a 25-percent rate as a Lookout in 2015, so he's made improvement despite the layoff, which is a positive sign for eager Twins fans.
Royals 1B Ryan O'Hearn, Class A Lexington: O'Hearn has a lot of obstacles to overcome to achieve prospect status. The left-handed hitter comes from a small college and fell to the eighth round of the 2014 Draft. Thus far, he's spent the bulk of his time at first base, suggesting his defensive contributions will be minimal. At 21, he's yet to play above the Class A South Atlantic League. Entering the year, he wasn't to be found on MLB.com's top Royals' prospects list.
And yet, the Sam Houston State product has emerged as one of the Minor League's premier power hitters, slugging 12 homers in 42 games as a Legend and 25 in 106 career Minor League games. O'Hearn homered in three straight games over the long weekend and has a 1.075 OPS in 22 games in May. He's roughly age appropriate for the South Atlantic League, and if he can carry those results over to the Class A Advanced and Double-A levels, he could emerge as an increasingly rare first-base prospect.
…and one not:
Giants OF Daniel Carbonell, Double-A Richmond: The Giants signed Carbonell out of Cuba on a four-year, $1.6 million deal last June and let him get his feet wet at the lower levels last year. The 24-year-old got a bump to the Flying Squirrels this year but has struggled mightily. In 37 games, Carbonell is batting .161 with a .377 OPS. Carbonell was a four-year veteran of Cuba's Serie Nacional, so it's disappointing that he's struggled so much in his Double-A debut.
Jake Seiner is a contributor to MiLB.com. Follow him on Twitter at @Jake_Seiner.