This spring four 19-year-olds started the season in Lake County. That certainly isn't unprecedented (last season four 19-year-olds also appeared in games with the Captains), but this group of teenagers all are among the organization's best prospects. All had very good seasons with short-season clubs in 2014, and all are in a full-season league for the first time in their young professional careers.
C Francisco Mejia
130 PA, .212/.305/.354, 24 SO, 14 BB
Signed by the Indians in 2013, Mejia has quickly become one of the best prospects in the organization. He's a switch-hitter who has the potential to hit for power from both sides of the plate. He also has a bazooka for a throwing arm, and although he'll need to refine other aspects of his game, he has the tools to be a starting MLB catcher.
Mejia started the season very slowly, hitting .155/.222/.276 in April. But it looks like he's started to adjust to the Midwest League, hitting .273/.385/.436 in May. However, a lot of his recent success has come as a right-handed batter; his OPS from the right side is .940, while his OPS from the left side is .542. That split is something to keep an eye as the season goes on.
On the defensive side, he's thrown out 29% (10/34) of potential base stealers (the league caught stealing rate is 30%).
SS Yu-Cheng Chang
164 PA, .253/.304/.384, 34 SO, 10 BB
Last year Chang played shortstop and third base while in Arizona, but this year he's played shortstop exclusively. The Indians want to develop him as a shortstop, even though he could probably move to third base and still be a viable major-league prospect. He's 6'1", tall for the position, and according to this profile was moved to the outfield by his coaches in high school, but the Indians see him as a shortstop.
1B Bobby Bradley
70 PA, .250/.386/.571, 26 SO, 13 BB
Bradley has spent some time on the Disabled List, but he's quickly made up for that lost time. He ranks second in the Midwest League in OPS (.957) and Slugging (.571), and is only teenager in the league with an OPS over .825. By just about every measure Bradley's full-season debut has been a smashing success. A fascinating statistic: Bradley, who bats left-handed, is tattooing left-handed pitchers to the tune of .353/.455/1.059, almost double the OPS he has against right-handed pitchers.
LHP Justus Sheffield
36.1 IP, 3.22 ERA, 8.4 H/9, 10.9 SO/9, 3.0 BB/9
The Indians have been limiting Sheffield's pitches per game (he hasn't gone more than five innings in any single start), but he's been impressive in just about all of his starts: in five of his eight starts he's either allowed zero or one earned runs. His 44 strikeouts ranks 5th in the Midwest League, and his 10.9 SO/9 ranks third against starters.
Here's a bit of video showing Sheffield pitching in Fort Wayne last week (it's towards the end of the highlight):