I disagree and actually think the chances of getting in as a deferred applicant from Rd 1 are pretty slim, probably the same chances as a normal waitlist if not less. If there are a 100-200 deferrees, as the letter says, maybe a handful at the most will get in. Here's why:
1. Historically, Sloan (according to one of their chats) sees 33% of their overall applications come in the 1st round, with the rest coming in the 2nd round. So they'll be more than likely getting twice as many applications in the 2nd round, which is more than enough to be able to fill out the rest of their slots. If they really wanted you at their school, the adcom would have already admitted you, yield numbers be damned. They wouldn't want to take the risk of losing you.
2. Most people who applied to Sloan in the first round applied to other top schools as well, and the candidates who were good enough to get deferred but not accepted at Sloan more than likely got acceptances at one other school, minimum. Surely the Sloan adcom does not expect people to roll the dice by denying those acceptances and keep their fingers crossed to get off the deferral list and accepted by Sloan. So, they must expect that the applicants are willing to eat well over $1K in deposit money and drop the other school like a bad habit if they come off the deferral list. They assume that Sloan is far and away the deferred applicant's number one choice, because again, if they really wanted the applicant and thought they had other top choices, they would have accepted the person in the first round.
3. Sloan requires no commitment from anyone to have the application continue to be considered, which means the only considering they're doing is whether to shred the paper copies or recycle them. All it takes it a simple click of a radio button to have the adcom continue to "consider" your application. They know that ultimately, most of the deferrees will probably choose to stay in the game because it doesn't cost them anything. It doesn't cost Sloan anything either. If Sloan really cared about whether or not someone actually wanted to still be considered, they would make the applicant post a deposit of ~$250. Three potential outcomes:
a. The applicant gets rejected/waitlisted on April 5. They will get the full deposit back.
b. The applicant gets accepted and decides to go to Sloan, so Sloan allows the $250 to be applied to the tuition bill
c. The applicant gets accepted and decides to go elsewhere. That's the price the applicant should pay for not being upfront about whether or not they are serious enough about Sloan to drop any other offers and go to Sloan instead.
The whole deferral process is really nothing more than a waitlist. I'm not sure I understand why they didn't just waitlist people instead of deferring them and giving them a false sense of hope.