I have to admit, I thought about just what you are asking. The 97's got a 99, but none of the wines were rated a 99. Seems strange, but I am no expert. It seems to me the vintage rating should be close to either the average or the midpoint of the wines tasted. I know if would never work out exactly, but you would think it would be close.
I have enjoyed the Castelgiocondo 97, both the Banfi 97's, and have yet to open the Casanova di Neri, but am looking forward to trying it. I haven't had any of the 97 Riserva's.