I think the odds of one of the big 3 falling to 7 all depends on what the Giants do. (Basically we need 4 QB's to go in the top 6.) Since we know the Browns and Colts will take 2 of the big 3 guys, that leaves the Giants as my main concern for the 3rd big 3 guy.
If the Giants go QB, that means 3 QB's are gone in the top 4 picks. Now at pick 5 the Broncos are the last worry. They can take a QB or trade with someone(Bills) who will take a QB. Now at 6, Colts take a big 3 guy, then at 7, we take a big 3 guy.
Browns - QB, Giants - QB, Jets - QB, Browns - Big 3, Denver(or trade partner) - QB, Colts - Big 3, Bucs -Big 3
If the Giants decide not to take a QB and go with a Big 3 guy, that drastically slims our chances with a Big 3 guy.
Browns - QB, Giants - Big 3, Jets - QB, Browns - Big 3, Broncos Big 3 or QB, Colts Big 3, Bucs - no chance for Big 3
Either way, i'm not getting my hopes up for Nelson, Barkley or Chubb. I will hope that if we miss out on them that means a QB is sitting at 7 and a team comes calling. If not, we all know it's Derwin James.