they definitely did in 2009 and 2010, but do they still feel the same way? Casspi did have a good rookie season, but from there he didn't improve. even worse, his output went south in almsot every possible category. that's why he also lost his starting spot to a player named Alonzo Gee, who couldn't even secure a roster spot with the Spurs.
but if they still believe in his potential, I can see how he fits. if Pop thinks he can play a role like Nocioni once did with the Bulls, or Jerebko plays with the Pistons, then he could find his niche. his size also makes him intriguing vs. Thunder/Durant.
I really can't see the Cavs buy him out. so it would need a trade. question is, what do the Cavs want? they are thin at SF, so they will likely ask for a SF. Spurs don't have. (KL is untouchable and Sjax to expensive)
a package of Blair and Neal might make them listen, but they will still take another teams offer, that includes a SF, over that package.
so, not the most likely scenario, also considering that at this point the Spurs priority would be a traditional PF.