The underachievement thing is right - the '88 and '89 Vikings were awfully talented (although not at QB), and all they could muster were 11-5 and 10-6 records and two asskickings in the playoffs by San Francisco. Pretty much the same team collapsed to 6-10 in 1990 after Keith Millard's knee exploded.
Viking loyalists are again starting their periodic whining that Burns and not Bill Walsh should have gotten credit for the West Coast Offense and using short passes to running backs. If you believe Paul Zimmerman, which you usually could on stuff like this, Walsh actually did it first not in SF but in Cincinnati in the early 70s, when Greg Cook got hurt and they had to adjust to Virgil Carter's weaker arm.