Pivotal

with players
    left merge results on player
    filter minutes >= 900
    goals_per_90 = goals / minutes * 90

with players as scoring_rates
    group by player
        agg mean goals_per_90
    sort goals_per_90 desc

players = players.merge(results, how="left", on="player")
players = players[players["minutes"] >= 900].copy()
players["goals_per_90"] = players["goals"] / players["minutes"] * 90

scoring_rates = players.groupby("player")["goals_per_90"].mean()
scoring_rates = scoring_rates.reset_index()
scoring_rates = scoring_rates.sort_values("goals_per_90", ascending=False)