That 48.5% figure should drop back down after next week. Mittens should get a huge margin of the delegates in Illinois, since it is winner take all by CD and effectively that way with the at large delegates, and Rick isn't on the ballot in four CD's. On the other hand, Missouri sort of has the same system of allocation, and Rick should get a huge margin there. However, the state has 17 fewer delegates than Illinois.
Illinois is shaping up as a state probably next in importance to only Florida thus far. It should be a barn burner. However, even if Rick wins many of the CD's, with his delegates not on the ballot in four CD's (it would be nice to know which ones, because if some or all of them are downstate, then Rick is really screwed), the odds are that Mittens will get all of the 12 at large delegates.
According to Erc's post on the 13th, it is the 4th, 5th, 7th and 13th that Rick doesn't have delegates.
https://uselectionatlas.org/FORUM/index.php?topic=145763.msg3215823#msg3215823Three of them are in Chicago. I was concerned that the 7th might end up like MI-13. ILL-01 and 02 have significant suburban portions that should dominate a Republican contest enough to give them to Mittens.
The 13th is a downstate seat. How Romney does in the cities downstate, will likely determine the vote in the 13th, as well as the 17th and 18th. Rick probably has 12 and 15 secured.