Your last name does not change because you are a junior. The junior goes with your first name. So Ken Griffey, Jr. was Ken Jr. not Griffey Jr. IOW, "Griffey" distinguishes him from the rest of the team just fine. If Joe Griffey was also on the team, then K. Griffey would suffice. If his dad was also then team, then I could see Griffey Jr. Otherwise, no.

It feels good to get that off my chest. Carry on.