I disagree. I feel the GM is responsible for the teams fiscal abilities first & foremost. Making Trades is # 2 on that list. Anything after that comes from a guy like McShay or similar in capacity.
No GM does the grunt work or pouring through hours upon hours of film. They may decide what to do fiscally with a player. Anything else you may hear is BS and we are Told for various reasons.
There's no way I will every believe Jerry, or Stephen for that matter, sits in the draft room and picks a player based upon their own work. It's based upon what the consensus opinion is between scouting departments, coaches, etc. McClay is now the ultimate opinion of those groups combined. He in effect is the guy who says "Jerry, Stephen this is the best pick/player/move for the Dallas Cowboys".
He is the reason we have Frederick & Terrance vs just Floyd and a year long pouting match that would ensue. Between various personalities.