Let's see, we have a top 5 Defense which as you stated, it's Secondary was it's biggest weakness, yet teams had no time to take advantage of it, and now with a another year under thier belt, the Secondary has become a little better, and are probably as good or better then last year .
The Offense of 07 will have more talent then the one in 06, and 05. If we had Green last year, and an O-coordinator that knews how to mix it up and keep the defenses guessing, Miami wins another four games (Don't forget, both Jet games, the 1st Bills game, the 1st Pats game, the Steelers game, and the Texans game were all winnable, and if not for bad QB play, a W was very likely).
This years with a GREAT defense, Miami is going to be sporting an Offense that at the very least will be good enough for another 7 points a game, which with our defense, that puts us in good shape in most of our games.
Finally, with all that we will also have a return game that probably will put our offense in good to very good shape every time they take the field (If the returner doesn't take it all the way). Not only is winning 11 games possible, but if this team gels quick enough, and gets enough momentum (Ala end of 2005), could 11 games be too conservitive a number?