It's so rare that SB winners grace the locker room of the Dallas Cowboys. How many ex-Patriots, ex-Chiefs, ex-Eagles, or even ex-Rams grace the locker room in Arlington? Not many. Why? Because they have been in places where the organization is run the right way and may actually influence the culture in a manner that Jerry and Stephen are not ok with.
Don't buy the culture change nonsense. What they don't want are vets that have seen how winners FO work because the Dallas build through the draft and re-sign your own model could get tainted. Most star Cowboys players have no clue what it is to play elsewhere. Hearing from Stephon Gilmore is definitely not what the Cowboys want Diggs, Parsons, DLaw, Osa, Prescott, Lamb, etc. hearing. It could taint how they view things. Normal won't be normal anymore.
So, you don't go after winners regularly. You sign FAs that have pedigree from franchises that don't win or don't players that don't produce on winning teams.
Sad but...it is the way of the Jones Boys, folks.