He beat Lacy and Kessler in their primes (both were good BTW), as well as guys like Eubank, Veit, Bika and Manfredo.
I'm not totally sure how you saw the RJJ fight for RJJ, but whatever.
The B-Hops fight you're totally misrepresenting. B-Hops was actually in the p4p top 10 (possibly top 5, can't remember) when Calzaghe beat him. He was still very much an excellent boxer, and you know very well that B-Hops is pretty much unnaffected by time (he also has the ability to never lose to white boys too).
Plus, who cares if you thought he lost both fights? I thought he won both fights (especially the RJJ fight), that's subjective. A lot of people thought Mayweather lost to ODLH and Castillo, is he not that great either? A lot of people though Whitaker beat Chavez, is Chavez not great? No, he's obviously one of the greats. Almost everyone thinks Joe beat RJJ and the B-Hops fight is pretty much split in the middle, give credit where credit is due.