Yet general manager Theo Epstein seemed almost giddy talking about it yesterday.

“We want all our prospects, at some point or another, to struggle,’’ Epstein said. “Make the adjustments and learn to overcome it.’’

There’s plenty to overcome at this point.

Kelly has allowed 47 hits and 16 walks through 37 1/3 innings. He has lasted a total of 12 innings in his last three starts, giving up 13 runs on 22 hits.

At 20, Kelly is the youngest pitcher in the prospect-laden Eastern League. When the former part-time shortstop committed to pitching over the winter, the Sox challenged him with a promotion.

“Obviously, the competition is better,’’ said Kelly, who dominated two levels of Single A last season. “As a pitcher, you have to adjust to hitters and figure them out. When you have games that don’t go the way you want, those are the games you develop the most as a player.

“I’ve had a couple of those games lately. I’m going through development.’’

Kelly’s mature outlook is a product of his upbringing. His father, Pat Kelly, played three games for the Toronto Blue Jays in 1980 and has managed in the minors since 1986.

The younger Kelly spent several weeks in spring training with the Sox and was told by the veteran pitchers that he could expect some hard times this season.

“It’s good for him,’’ said Jon Lester, who lost six games pitching for Portland in 2005. “You learn a lot when it doesn’t come easy, like it did in high school.’’

For Kelly, the learning process includes becoming more adept at working from the stretch and holding runners, two aspects of pitching that rarely came into play in high school. He also can’t rely on his fastball to put hitters away.

“He’s not getting away with his mistakes,’’ said Epstein. “When he’s on the corners and down, he’s getting ground balls and weak contact. But against better hitters, he can’t get away with mistakes up.’’

Kelly agreed with that assessment. The velocity and movement of his pitches have been fine. It’s the location that has been lacking.

“I’ve had runners on base and left some pitches up in the zone that I paid for,’’ he said. “It’s frustrating, but those things are going to happen. I can’t lose my focus on the next pitch.’’

The Sox will be content to let Kelly spend the season with the Sea Dogs and get a full season of pitching on his résumé. He remains at least a year away from challenging for a spot on the major league roster.

“This year is going to be great for him,’’ Epstein said. “He’s going to come away having learned a lot.

“We’re happy he’s there, because this is what he needs. Another year in A ball would not have helped him.’’

Kelly believes he one day will look back on this season fondly, even if there are growing pains now.

“Hopefully someday I’ll remember these games as I time when I learned a lot about pitching and that it helped to make me successful,’’ he said.

Peter Abraham can be reached at pabraham@globe.com. Follow him on Twitter @peteabe.