Here's the thing....
Starting Tony over Ray would be a complete, 100% panic move. As bad as Ray's confidence is right now, it would likely be completely shot after that. Can you imagine the furor that would arise if Doc actually DID this? This would be worse than Lil' General panicing and going smallball against Golden Sttate last year.
We win the title this year if Ray breaks out of his slump. If he doesn't, I don't see how we get past both Detroit and whoever comes out of the West. Look for them to try and get Ray going early in the first quarter, and look for Ray to attack the rim. If he can't get it going, I wouldn't be surprised to see him have a pretty short leash - but that means Pierce at the 2, Posey at the 3, and maybe a bit more Eddie. Tony will be lucky to break a sweat (nor should he - he's fallen out of the playoff rotation for a reason, he's just not that good, and he's unreliable).
As noted, Detroit has to pay attention to Ray whenever he's on the court. They know that if he DOES get going, they're in a lot of trouble. He could be 0-20 and you still wouldn't leave him open.
(I feel like I'm telling you that Santa Claus doesn't exist, but don't get your hopes up for Tony being re-signed in the offseason, either).