Grading NFL general managers is not a simple process. Most are happy with hit rates of 50% in the draft. Most make mistakes in free agency. Most haven’t created perfect rosters because the salary cap makes a “perfect roster” impossible. Most get a coach hire wrong at some stage.
Ryan Pace took over the Bears after they had just completed the most embarrassingly pitiful defensive season in franchise history. He took them over after a season where they embarrassed the city and fan base on and off the field. Five years later they have the most talented defensive roster in the league.