Then came some unexpected news.
"My mom, she had surgery and in the middle of the season I had to go take care of her," said the 19-year-old Acosta. "She fell through a ceiling and broke her foot and fractured her spine, so I had to go take care of her in the middle of the season."
That was in mid-to-late May. When Acosta returned from a leave of absence, in late June with the Mesa Cubs of the Arizona Rookie League, he made three appearances before he was shut down.
The layoff, which Acosta described as being equal to coming back from an entire off-season, contributed to a stressed elbow, and tendonitis in his shoulder and biceps.
"I always try to keep my body in shape and what happened was … I never really fully developed back into it, so it really was like coming back from an off-season," said Acosta.
He was slated to attend the Cubs' Instructional League in Arizona this month, but those plans were shelved. Cubs Vice President of Player Personnel Oneri Fleita said Acosta was still "tending to family business."
Acosta says he feels fine now physically.
"It was just a series of bad things," he said. "I had a little bit of tendonitis kind of come back from the break. I'm too young so they really don't want to push it too much."
Acosta, the son of the late former Cubs pitching coach Oscar Acosta, says he was still able to revel in plenty of knowledge and take some overall positives from his shortened season.
He finished 1-1 with a 4.19 ERA in eight starts spanning 34-1/3 innings at Peoria.
"It was different to sit around and watch different guys that are older than me, to learn the game, and to watch [Chiefs manager Ryne Sandberg] and [pitching coach Rich Bombard] handle things and situations that go on, on the field," said Acosta.
"To sit there and learn stuff from people that have been in the game for a lot longer than I ever have, you learn a different thing every day if you watch and study it.
"I always thought that competing with people that are better than you or just as talented always makes you a better pitcher. I would sit and watch those guys (hitters) and how they approached the play and how they handled certain pitchers and what pitches they hit good. That's what my part was. It's not like you just pitch one day and the next day is your off-day.
"My big thing was I'd sit there and try to find something and get as much information as I could. The day before and the day of (Acosta's starts), I would go back through that information and try to use it as a game plan."
So what did Acosta learn specifically? He said the one thing he took from his season was simply that ‘everything counts.'
"There's not one pitch that you can throw without having total concentration, total effort and a meaning behind it," Acosta said.
This is not a bad thing, Acosta says. The more zoned in a pitcher with his talents is, the more dangerous he becomes in essence. His repertoire is somewhat basic: fastball, slider, curve and changeup. He also has a splitfinger, but the pitch is temporarily on hiatus because the Cubs want Acosta's arm to get some age and experience before it becomes part of his full arsenal, he said.
Acosta said he plans to spend the current offseason building up his endurance (in the eight starts with Peoria, he made it past the fifth inning only once). He says that all comes back to the ‘C' word: concentration.
"My main focus this off-season is pushing it past the fifth inning," he said. "I'm going to push my body real hard this off-season and try to make the best of it because I found out that if you don't press further than what you've already been pressed, then how are you ever going to find out what you can do.
"There were a lot of times in Peoria where I would shut people down for five innings and go out in the sixth inning (without) my full concentration. They'd come back on me; they'd get a couple of hits and I'd give up a couple of runs. The big thing I think is for me to focus on the overall mindset of every pitch."