The 24-year-old Rosario (19-1-1, 13 KO) obviously isn’t most people’s first choice for a debut defense, but he makes sense rankings-wise. On the IBF side, the three head of him are Carlos Adames (near-guaranteed to fight Patrick Teixeira for the WBO belt once Jaime Munguia moves up), Jarrett Hurd (already said no to the rematch), and Bakhram Murtazaliev (just fought two days ago). The only feasible options on the WBA side who aren’t already booked or otherwise occupied are his fellow “champions” and maybe #6 Israil Madrimov, who is nobody’s first choice for a debut defense.