The Pirates will be sending three position players and four pitchers. We now know that the position players will be infielders Brock Holt and Jarek Cunningham, and outfielder Robbie Grossman. Three of the pitchers will be Nate Baker, Phillip Irwin and Mike Colla. That leaves one spot for a pitcher, and Kristy Robinson tweeted that the roster for Pirates instructional leagues indicated that Cole would only be there for two weeks, and would head to the AFL after that.
At this point, who knows? But given that Cole didn't really have enough time after signing to pitch in the minor-league season, and that a college pitcher from a big program like UCLA should be able to handle fairly high-level minor-league hitting, sending him to Arizona makes perfect sense.