I try to give the credit where it's due, but I'm not overselling anything. Stephen Jones and Will McClay both pre-date Jason taking over the team. The improved drafting coincides with Garrett taking over and Wade's departure. If you want to give the credit to Stephen, fine, but listen to what he has to say about Jason some time, then, because those guys are on the same page.
At some point, you look at how the team got better under Parcels, how the talent peaked and then dipped under Wade, and then how it improved again under Garrett and just give these coaches credit (or blame) for what their teams have done. We can pretend that Parcels was the reason they got good in 2005-2007, Wade the reason they dropped off in 2010, and then Stephen and Will McClay were the reason they started suddenly improving again under Garrett if you really want to. That's pretty contrived though. The much simpler explanation is that Bill was a good coach in Dallas (even without any playoff wins), Wade was a good change of pace for Bill but ultimately unable to lead the franchise effectively so his team peaked and then fell off, and Jason came in, restructured the scouting department, changed the staff, promoted McClay, and worked with Jerry and Stephen to rebuild the team again into the contender it currently is. As with most of these things, the simplest explanation is often the best explanation.
Either way. Fingers crossed we get those Superbowl wins so your estimation of the HC can go from 'not sure if he's good' to considering him 'great.' As you say, no excuses. It's time to prove it.