To me, it seems a little unfair to hold Dak against any individual GM. It would be one thing if Pace passed on a franchise QB in the 1st round who was highly thought of and who turned out to be good (like the Browns passing on Wentz). Then we would be able to clearly say, "hey, this guy is terrible, let's move on." I don't think you can point the finger at Pace when the collective intelligence of all 32 GM's (including football genius like Belicheck), millions of dollars of resources, and the entire scouting system failed by letting a franchise QB fall to the 4th round (assuming he keeps playing at this level, which definitely is not a given).
Even the Cowboys clearly had no idea or they would have drafted him earlier than the 4th. In my opinion, the Cowboys got lucky just by virtue of having Dak rated as a slightly less shitty QB than the next team who would have been willing to draft him. So now they get to brag about how "smart they were" and how they knew there was something "special" about the QB they wouldn't draft until the 4th round for as long as Dak can keep it up.