1. A player's medical report is very comprehensive. Sorry I've linked this a million times already, but it's basically every exam, every interaction with trainers, every treatment recommended, and the results of those treatments. It's absolutely possible that some data in there would shift their original forecast for Graterol, as compared to the publicly available information: https://www.bostonglobe.com/sports/redsox/2020/02/06/how-baseball-teams-exchange-medical-information-after-agreeing-trade/Nu56T96T3GENiqQQs0amZN/story.html?outputType=amp The fact that the Twins were willing to deal Graterol for Maeda suggests that there's some pessimistic non-public info on Graterol. Perhaps this should have been a hint to the Red Sox, although the extent of it may not have been known. And of course the nature of such analysis is going to be subjective -- not every team or trainer is going to look at the medical report and agree on the same forecast for the player. For example, the Twins may have given him 30% odds of returning to starting and conveyed that to the Red Sox during negotiations, but after the medical review, the Red Sox independently may have thought it more like 10%. Rumor suggests that the Red Sox did request Balazovic in place of Graterol, and the Twins declined. I'm sure they asked about Dodgers pitching prospects earlier in the process too and were rebuffed, hence how the Twins and Maeda got involved in the first place. Graterol is still a good pitcher with value. The Red Sox likely wanted a young pitching component to the trade, and it seems that Graterol was probably still the best young pitcher the Red Sox could feasibly get, even if it his forecast value wasn't as high to them after the medical review.