My rookie team have 8, 3 - 150, 2 - 100, 3 - 50. But you can a create a lot of cap space depending on your Playbook, like using only 2 or 3 WRs plays. Also, you can hire only 1 HB, QB, C, SS, 2-3 WRs. But i've seen a lot of sucesfull high tier teams with 6-9 S*s.