Full strength Rondo, I'd say we're easily 2-2, if not 3-1. We'd have won vs the Bucks and Grizz, and I could see us having beaten one of the other two teams as well. It's not like we're getting blown out. We just have nothing going in crunch time.
Of course, I doubt we'll be getting back full strength Rondo for a while after he returns. I hope C's fans watch how Derrick Rose has been playing and adjust their "when-Rondo-returns" expectations accordingly. And it could be worse than Rose -- a lot of the key Bulls played with Rose before he got hurt. Rondo's had a half-season with Green, a half-season with Sullinger, 2 months of Bradley in 2012 when he started to get PT, and maybe a month last season... Really Bass is probably the only Celtic Rondo has played with somewhat extensively. Rondo has to recover, get back to game speed, learn a ton of new teammates, and learn a new coach. I doubt the adjustment will be instantaneous.
That said, with any version of a healthy Rondo we beat the Bucks. So 1-3.