Let's compare two hypothetical teams, both of whom go 4-1
Team A beat a 3-2 team, two 2-3 teams, lost to a 1-4 team and beat an 0-5 team
Team B lost to a 3-2 team, beat two 2-3 teams, and two 1-4 teams
Team A has the better win, but the weaker SOS and the worse loss. So whether you beat better teams doesn't always mean a stronger strength of schedule