Pg-rubio
Sg-
Sf-melo
Pf-bargs
C-ibaka
Offense will not be a problem. Rubio will be able to create for others, and you have good shooting from Bargs and Melo.
I think this team absolutely needs an elite defender at the 2.
Rubio will be a little slower/weaker as he recovers (hopefully fully) from that knee injury. Melo can play passable defense, but Bargnani is a real negative in that respect. It's possible Ibaka may end up committing fouls trying to recover from the overall porous defense of his teammates.