That's what you pay scouts for. To find these type of guys. Teams find them all over the draft. And you know what's funny is that those studs with premium pass rushing traits who teams gamble on in the 1st usually end up being busts.
While guys like Conner Bawrin, Justin Houston, James Harrison, Cameron Wake, etc. fall through the cracks.
They don't have to be Demarcus Ware. Just find pass rushers.
Again, you can find pass rushers anywhere, even as an undrafted free agent but scouts are looking for premium pass rush traits which are typically found in the early rounds especially if you need a starter.
Sure, players can demonstrate these traits in later rounds and can develop these traits but probabilities in terms of a premium skill set as pass rusher like a Ware and Watt are found early.
The draft is about probabilities and there is always risk and the unknown, scouts are paid to evaluate and mitigate this risk as much as possible by proper adjudication but in the end it is all about probability quotients.
Sure later round picks and undrafted free agents which demonstrate these traits are drafted and signed with some actually turning out better than those who were drafted high.
However, probabilities of these type of players being relied on to start immediately with the purpose of offering a premium pass rush early in their career is rare and not the rule.