Wow, it's just one sentence, but you fit in three wrong statements- that's tough to do. 1- He wasn't "oldish" when he broke out. He was 19 or just turned 20 when he broke-out in Short season A ball. 2- No arm injury. 3- He didn't lose a year of development. He got eight starts in in AAA and very well could pitch in the fall and winter. To be honest, there was some excitement around Alzolay when he was an 18-year-old in the DSL after putting up this line: 67 IP, 49 H, 10 BB, 61 K, .201 BAA, 0.88 WHIP and a 1.07 ERA. That's why I've been intrigued by 18-year-old LHP Luis Rodriguez this year who's mid-season line reads: 26.1 IP, 12 H, 4 BB, 28 K, .133 BAA, 0.61 WHIP and a 1.03 ERA. I have no idea what Rodriguez's stuff is like, but then again, we didn't know anything outside of Alzolay's stat line back then either. Alzolay then had an off year in the AZL (as a lot of DSL success stories do) with a 8.51 ERA there, but returned to impress in the NWL the year after that. The first reports of his stuff that year were average (91-93 FB, decent off speed, no change up). The anticipation of his performance in full season the following season was followed by disappointment, however. The league hit .260 against him with a 4.34 ERA. His K-rate dropped significantly. He was/is undersized and many thought he'd wind up in the pen (which he still might). 2017 was another story. Preceding that season, reports out of Mesa were that he had taken a step forward in velocity and command both with the FB and curve. He had also begun working on a change up that flashed but was still below average. He truly broke out as a 22-year-old, dominating High-A and finishing acceptably in AA. He was consistent 94-96 with a plus curve and was hitting his spots with both. The biggest change was in his confidence and approach. He notoriously, and to the dismay of many batters, would get the ball back from the catcher and deliver the next pitch within 5-10 seconds. He eliminated thinking, trusted his catcher and didn't allow the opposing batter to get comfortable. All things he wasn't doing in Eugene when he was 20, not 19. He had turned 20 three and a half months prior to the start of their season. He most definitely has lost time on his developmental track as, without the lat injury, there was high expectation he would see the majors this season. Given the injuries and ineffectiveness in the Cubs rotation this year, that would've come in handy. He may still pitch in the Arizona Fall League, but that is yet to be seen and certainly wouldn't replicate a full season of experience developing his change up which was, according to interviews given by Cubs brass, the final piece in his development before being brought up with confidence of major league success.