Anyone know how they work them out?

Just watching Kembla Grange race 3 and I noticed that the 5 Emilion, was a ratings special.

Now the 7 Orkan Sky, which had 1 start for a flashy finish to be beaten into 2nd in a photo was to start favourite.

Now how can a horse that has 0 starts, be a ratings special over a horse with 1 second from 1 start.

And Emilion won. What do they know, and what are they basing their ratings on if not previous form?