None of these guys are (hopefully) rotation players. They are invites to compete for the 14th and 15th spots on the roster.
I take the opposite view. Hopefully, at least one of these guys is a rotation player, because this team needs cheap talent and one way to get that is to find one of those guys who could be at least a back-of-the-rotation guy on most NBA teams if given the opportunity, but just hasn't gotten the opportunity.
If your choices are guy in his late 20s who never really caught on with a team in the NBA and ended up bouncing around Europe or signing a guy like DJ Mbenga for the minimum, I'm willing to take a chance on the unproven guy if I think he has the mental tools to succeed.