Here's Bill Walsh's first draft, what you'll find looking at his career drafts is he got one, sometimes two game changers a draft. Bill Belichick does about the same because that's about the best you can do, the glue guys make the difference. Nobody does it better... as good maybe, but not better.
Rd. Player
2 James Owens
3 Joe Montana HOF
5 Tom Seabron
5 Jerry Aldridge
6 Ruben Vaughan
7 Phil Francis
9 Steve Hamilton
10 Dwight Clark
10 Howard Ballage
11 Billy McBride
There was a RB taken a round prior to Montana, he was a bust. The only serviceable players here were Montana and Clark. Does Bill Walsh suck because of the busts or is he great due to his hits?
Here's Bill Walsh's 2nd draft class...
Rd. Player
1 Earl Cooper
1 Jim Stuckey
2 Keena Turner
3 Jim Miller
3 Craig Puki
4 Ricky Churchman
4 David Hodge
5 Ken Times
6 Herb Williams
8 Bobby Leopold
9 Dan Hartwig
Do any of these names jump off the page, can you recognize a single player?
Probably not because beyond Keena Turner, who became a role player, the entire draft class was a bust.
The notion that there is some GM out there who hits on all or the majority of their picks is horsesh-t. It doesn't happen, or maybe once in a blue moon.
Bill Walsh is considered The Godfather of the draft, the guy's methods are the ones most scouting programs are based off.