If he was ready for MLB, he should have been better in July and August of 2014 (which were his best months of last season so I'm not cherry-picking here). July: .250 .282 .471 .753 August: .248 .289 .425 .714 The guy had a New Britain OBP of around .285 in July and August. It was 231 PAs so we're not talking about an insignificant amount of playing time. That doesn't look like a guy who's ready to face MLB pitching. He had ~250 PAs before that time to shake off the suspension rust so that can't be used as an excuse for his mediocre play. Sending a guy who played a shortened season in 2014 out against MLB pitching - a guy whose .285 OBP in AA screams "can not identify a pitch" - is asking for Aaron Hicks, Episode II. If the guy can't identify AA pitching and lay off the occasional pitch, MLB pitchers are going to crucify him out there. Rosario isn't Ben Revere; he's not an extreme contact hitter so you can (somewhat) overlook his lack of walks. Eddie isn't a strikeout machine but he's not particularly good at making contact, either. That tells me he struggles with recognition and guesses a lot. If Oswaldo Arcia struggles with that problem in MLB, it's likely that Rosario will be embarrassed in MLB should he be promoted too quickly (Oswaldo is a much better hitter than Rosario and his wrists are lightning fast, allowing him to compensate for guess swings a bit).