The league has 16 teams, which means in an even spread of talent, each team would only wind up with 1.25 players on the list. Of course the talent isn't evenly spread, so there were teams left out from the list. It was also apparently a very deep year for talent in the league. With that coinciding with a lackluster 'prospect' team on the field in Dayton, the lack of a Dragon on the list is unsurprising.
The Padres placed 5 players on the list, while the Blue Jays had 3 and the Cardinals, Twins and Royals each had 2.