Drafting high school-level arms with such an early pick is virtually always a massive risk. Sure, every single player in the draft pool comes with a significant amount of risk; but the younger the player, the more of a wild card they are. In both good and bad ways.
In the case of Barriera, the Blue Jays drafted him first last season, but he did not make it into any professional games until early in the current campaign. After easing into action thanks to a shoulder injury, he made it into a total of four games before going back on the shelf with elbow soreness. In the four starts he made, he surrendered nine runs (eight earned) on eight hits in just 13.1 innings of work, good for an ERA of 5.40.
Keith Law of The Athletic made some interesting comments about the former first rounder, and it sounds like Barriera showed up to camp with a bit of extra weight added. That, paired with his immediate placement on the injured list, has done enough to turn the Blue Jays off from selecting another high school pitcher so early in this year's draft. In the very same piece, Law predicts that the club lands shortstop Jacob Wilson in the first round, which would be an excellent choice.
The fact of the matter is that high school players are always going to be huge risks. At 18 or even 19-years-old, teams have to count on shaping said player(s) themselves, while college-level players come with additional experience and seasoning, so they aren't quite as big of a project for their organizations. Collegiate players also come with considerably more statistical data behind them, whereas many high schoolers have not yet had their games exposed to such deep data tools used noawadays.
There are quite a few collegiate arms that will be available by the time the Blue Jays are up to make their first-round pick. Ty Floyd (LSU), Hurston Waldrep (Florida), Brandon Sproat (Florida) and Joe Whitman (Kent State) are some of the players Law has being taken around the Jays' pick in his latest mock draft piece.