The prospect with the most hype this past spring amid a sea of talented youngsters was easily Vladimir Guerrero Jr., but on March 10 he suffered an oblique injury. He was unlikely to start the season in the majors anyway, due to service-time manipulation, but this removed all doubt (and took the Blue Jays off the hook, some might argue). 

He's now healthy enough again, and he's already seen action at the Triple-A level. Oh, and he's also already homered: 

Guerrero, 20, hit .381/.437/.636 with 29 doubles, a triple, 20 homers, 78 RBI and 38 strikeouts compared to 37 walks last season in 95 games (one at Class A-Advanced, three in Rookie Ball, 61 in Double-A and 30 in Triple-A). So it's not surprising that he'd start hitting right away. Though Guerrero had tough competition from the likes of Fernando Tatis Jr., Pete Alonso and others, he was the near-consensus top prospect in baseball heading into the season. 

As for his near-term future, he won't be able to earn a full year of major-league service time in 2019, which means the Blue Jays are now "free" to promote him on the merits. Speaking of which, that figures to happen soon: 

"Soon" could mean a lot of things, but it's doubtful one of the highest-ranking team execs would say this on the record if the Jays didn't have plans to promote Guerrero Jr. in the very near future. Developing!