@'stache
The problem with the Cowboys isn't necessarily that they are poorly run. In fact, they've been fairly successful during the REGULAR SEASON over the last 20 years. I believe the stat is that they are the 8th winningest franchise during the regular season since Parcels took over for Campo (of course they're the only team within the top 10 over that span of time to not make a Super Bowl, much less a conference championship).
No, what's wrong with the Cowboys has more to do with how Jerry's influence changes how head coaches deal with the team personnel. Be it certain players getting playing time over others due to being more marketable (ie Zeke, Jaylon Smith, and maybe even Witten at the end of his career), or the way Jerry's presence and relationship with the players limits a coach's ability to instill discipline or to be the final word of authority over the team. Even the way being a member of this team impacts the manner in which a player sees himself (ie Ceedee Lamb behaving as a star the moment he put on the uniform).
There was a recent podcast interview I saw with Michael Irvin and the guy on the podcast asked Irvin what it was like for him when he arrived in Dallas. The interviewer had just asked the same question of Micah Parson and was clearly asking from the standpoint that Dallas Cowboys were always perceived as stars from the moment they arrived in Dallas. Michael shocked him with his answer when he reminded him that they Dallas Cowboys weren't treated in that manner in 1988 and none of the benefits now attributed to just being a Dallas Cowboy arrived until AFTER they won a Super Bowl. It's difficult to put a finger exactly on the specific way that Jerry's management style does to limit the team's performance, but it's clear that it does.