I was looking back over basketball reference at past MVP winners, and since 1978, the year turnovers were first recorded(a key component in calculating PER and win shares), Steve Nash's MVP seasons are the two lowest in terms of PER, and the second and third lowest in terms of win shares. Only Bill Walton, who coincidentally won the award in '78, had fewer win shares his MVP season, and Walton is unquestionably the least deserving winner of the last 30 years(not because he wasn't good, but because he missed 24 games, nearly a third of the season).
Nash's MVP seasons are also the worst in terms of defensive rating over the same span, but I don't think there's much debate over whether or not Nash is the biggest defensive liability ever to win the award. I don't put much stock in defensive stats, anyway.
