Fives is quite good with protection, OP would be a bit of stretch though.
Yoda, RG and Daka or Dooku are your friends, so just stunlock him and he can't counter =)
He doesn't hit very hard outside of his counters and is pretty slow so overall he seems pretty balanced other than the crazy tanking ability he has.
For example, i only unlocked him this week and got him to 4* and he's almost gear 9 already (very very easy to farm gear for thankfully) and has 25k health. However, he only hits for about 1-1.5k per hit and has 115 speed so it'll only be once i get his basic to maximum that he's going to start dishing out the hurt.