The Minnesota Vikings’ competitiveness
There has always been a clear weak link in their division.
After Green Bay won those first two Super Bowls, they had like 3 winning seasons total until 1992.
Tampa Bay was so bad the division petitioned to have them removed.
Chicago has been in a rut pretty consistently as the NFL has prioritized the pass more.
The Lions (which was sufficient enough to say until about a year ago)
They excel at keeping good things together and making swift changes while remaining patient through the change - even when their ownership had zany things going on in their lives.
They have also tended to have consistently good or decent drafts historically and Herschel Walker super'bust trade aside, their FO and ownership rarely make rash, dumb, stupid decisions when it comes to trades and FA signings.
The Lions weren't a particularly bad team in the early 80's with Billy Sims as their proto-Sanders esque RB and strong "Silver Rush" defense of Al Baker, Doug English, Dave Purefoy, and Stan White, at least until Sims suffered his ACL career-ending injury in 1984 season. Detroit made the post-season 5 times with Sanders as the offensive weapon although they still under achieved on offense despite having some great WR's in Hermann Moore, Johnny Morton, Brett Perriman, and TE David Sloan. The biggest, glaring issue was lack of a Pro Bowl QB and Scott Mitchell didnt fit that mold even if he was a bit of a tease at certain points.
The Vikings four SB losses, while notable and noteworthy, have to be viewed within the context of the power and quality disparity and overall competitiveness between AFC and NFC teams from the late 60's-early 80's. In the 1970's, unless you were the Dallas Cowboys, even if you were a perennial playoff team like Redskins, Vikings or Rams, compared to Oakland, Pittsburgh, or even San Diego and Miami, you and your conference were perceived as very inferior to the AFC.