Red Sox land their ace in Garrett Crochet: Fantasy outlook and breakdown of the trade
Point blank, the Red Sox needed an ace. They also needed at least one left-handed starter. They were apparently close to landing Max Fried, and they never seemed locked into spending what they needed to land Corbin Burnes (which they still might). Apart from those two, Crochet was the only other legitimate ace remaining, so the Red Sox swooped.