Why, the head coach drafts the players.
Since you can't understand a simple concept, I'll lay it out for you...
A head coach should have a lot of say in which players come in, especially for scheme purposes.
Ryan brought in a bunch of players on defense that knew his scheme so he could get things rolling early. That was his call.
An offensive head coach would bring in players that would be fits into his offense, and it would help the transition from complete garbage to mediocrity in the first season.
For some reason, you think NFL coaches come in and just let the GM bring in whoever the hell they want without consultation. That's not how it works.