I believe the over-valuing our own players is a result of the desire for self-validation by the Cowboys front office.
I think the fans are just as guilty of this though, but for different reasons of course, as we tend to want the team to keep players that played well and/or showed improvement recently.
The Cowboys need to stop waiting to find out how good their young players are until the last year or two of their contracts.
For years I have said that the Cowboys should use the draft and rookie free agents more aggressively than they have.
I think the reason they do not do it is because they have this old school flawed mentality that most players need to be on the team for 2-3 years before they become starters.
That leads to the team seeing one good (or even great) year from a player and then have to start thinking about resigning (and overpaying) them based on that one good season.
If you think about it, most of the non-first round rookies who have had great first or second seasons did so more due to injuries to other players than the wisdom of the front office or coaching staff to make them starters.
As a fan, there are players i like so I am glad they keep them, but the front office and coaching staff need to stop applying the same progression path to every player and instead start thinking about letting some of the players show what they can do right away.
Best case, you find a star player who can help you for years before you have to pay them a higher contract. Worst case, you realize sooner than in the past that they are not the answer which allows you to start looking for the next player.