Shaq-Marion?

I'd like a bit of what the Phoenix Suns are smoking if they're seriously contemplating this deal. I understand that there are some Marion-related chemistry issues, but he's six years younger than Shaq and already at this point in their respective careers Marion is more productive. Shaq's going to mesh with Phoenix's up-tempo offense? Who's going to replace Marion as a wing defender? It doesn't make any sense.