Just researching some things, found these to stand out. Curious what people think.
My thinking on what makes each especially hard:
For FSU, you basically had to win every bowl game during the run, or like 95% of them.
For the FL programs, you reply on other programs to contribute, all within one state...and they didn't exactly take turns being good.
For the SEC one, it included 4 different programs, luck in the voting, etc...a perfect storm type of thing.
For Alabama, you need your coach to stay put and to fight complacency, which is extremely difficult - many say staying on top is harder than getting to the top.