Actually, while you may poo-poo the schedule issue in 2000 in an effort to minimize the legitimacy, it's a valid argument. The only team with a losing record that they lost to that season was NE* (5-11) at home, a game which Johnson started but was knocked out in the second quarter with NE* up 3-0, which goes on his W-L, but which they lost in OT 13-10 with Flutie in the game. Otherwise, the Bills that season split with the Jets (9-7), lost both games to Indy (10-6), lost both to Miami (11-5), and lost to Tampa Bay on the road (10-6) with Johnson starting. They lost to Minnesota (11-5) on the road with Flutie starting.
The Bills beat Tennessee (13-3) at home, Green Bay (9-7) at home, San Diego (1-15) at home, and Kansas City (7-9) on the road with Johnson starting, and beat the Jets (9-7) at home, NE* (5-11) on the road, Chicago (5-11) at home, and Seattle (6-10) on the road with Flutie starting.
Regardless of QB play that year, they were a middle of the road team with Eric Moulds, Ted Washington, Pat Williams, a few aging talents, and an otherwise non-descript roster that was about to undergo a salary cap purge, and were being managed by a GM whose heart was already in San Diego.