When Jimmy won those Superbowls(yeah, idiot Barry won one with Jimmy's team), Jerry's ego was really pumped, but it was more than tempered by the fact that winning Superbowls actually cost a franchise money. Jerry himself made the comment that he lost money winning the Superbowl.
Jerry bought the Cowboys to make money. The way to maximize money with an NFL club like the Cowboys is to look competitive, but not be a top contender. If you are a terrible team, you will have trouble filling seats, getting good advertisers, and selling licensed team related goods. On the other end of the spectrum is is the money losing Superbowl contender. Your money will be maximized if fans have continual hope that you will advance into the playoffs, but come close and fail to make it, or lose in the first round.
The other thing you do is get a city to actually pay for a good deal of YOUR new stadium. That way the value of your franchise goes up without you having to pay anywhere near market value for your new stadium. We have had two good coaches with the Cowboys. Once Jerry produced his loss leader with Jimmy, he only hired the other coach(Parcels) to bring the team back to a competitive level, but not stay long enough to make a winner, as the team was sliding too far down the hill and would begin to affect profits.
Hire a GM ? Why would Jerry hire a guy to win ? He doesn't want to win. He wants to MAKE MONEY. A real GM would tell people Jerry doesn't want to win. Jerry and his other carnival barker friend Al Davis, were the biggest pushers for a salary cap. Once that was done, other owners and GM's gave Jerry a lesson on how to manipulate a cap and still win. That was okay, Jerry was only interested in the money.
Congratulations to the Jones family on turning a class NFL organization into a football version of professional wrestling. Fool me once, fool me 17 times(years). I have watched the Cowboys religiously for 40 years. Jerry has cured me of that.