I don't see Diaz getting any bulkier, even with a rs year, and therefore no more of a force on defense. His only unique attribute is his height, which is useful.
But I think DJamer offers a more realistic option. Someone mentioned on another thread that Diaz doesn't like to play with his back to the goal. And if it is going to come down to teaching one person new tricks, or trying to get someone to forget all of their old tricks before learning the new ones, you go with the simpler process.
oscar Diaz.