Football is a team sport.
On any play, one guy not doing his job means the play fails.
That's what makes the NFL GM's job so tough. They have to judge what these guys would have done in functioning offense if they played with the same skill and ability, then they ALSO have to judge the potential development of the guy once they reach the NFL.
Washington having so many guys drafted tells you one of three things:
1) A lot of the rest of the guys on the team made a lot of mistakes or had little talent
2) The coaching scheme did not take advantage of the talent
3) The scheme required the talented players to play a certain way, and the different way they will play in the NFL better fits the specific skillset of a specific player
I'm never sure why people expect the NFL draft to be littered with guys from the top teams only. Take a look at the all-pro rosters sometime. Lots of guys from "bad" college teams and small schools.