the 10 years bit is stupid, but good teams go through 5ish year runs with a certain core of players and coaches. you can see that Seattle & Green Bay are at the back end of theirs and are in the process of retooling around their all world QBs.
Atlantas should be early in theirs but losing Shanny threw a wrench in things, Minnesota's about halfway through theirs but that's why they were so desperate to not let the Teddy injury derail them and they jumped out the window with the Bradford trade. Panthers are closer to the end than beginning and that's why Rivera made his move for Norv.
Eagles, Rams, and Saints are all just at the start of theirs. Saints clock is ticking since their QBs obviously older, but he's still going strong and an all time draft class has them right in the mix.