Bobby Orr Won the Art Ross, Hart, Norris and Conn Smythe in One Season
In 1969-70 Bobby Orr won the scoring title, the MVP award, the best defenseman award and the playoff MVP award in the same year. No player in NHL history has done that, and no other defenseman has ever won the scoring title at all.
Orr won it twice, in 1969-70 and 1974-75, and he is still the only defenseman to have done it once. He took the Norris Trophy for best defenseman eight consecutive years, from 1968 to 1975, a run nobody has come near. He also won three straight Hart Trophies as league MVP, from a position that is not supposed to produce them.
The 1970-71 season is the outlier even by his standards. He scored 139 points, which no defenseman has approached, and finished at plus-124. That plus-minus figure is the single-season record and is not seriously threatened; across his eight Norris-winning years he was plus-563. He was, in the most literal statistical sense, the reason his team outscored people.
What he broke was the job description. Before Orr, a defenseman carrying the puck into the offensive zone was a defenseman out of position, and the position was defined by what a player prevented. He rushed end to end, quarterbacked the power play from the blue line, and won two Stanley Cups doing it, including the 1970 final he ended himself with the most famous goal in hockey.
The case against him is 657 games. His knees were destroyed by 30 and the career is short enough that his counting stats are modest. Nicklas Lidstrom won seven Norris Trophies and four Cups across 1,564 games with a consistency Orr never had the chance to show. Doug Harvey won seven Norris Trophies and six Cups. Ray Bourque has far more points than Orr and played twice as long.
Lidstrom is the better bet if you are picking a defenseman for twenty years. But no defenseman has ever been the best player in the entire league, and Orr was that for about six seasons, with four trophies in one year to prove it.
The verdict: Bobby Orr. The knees cost the sport its greatest unfinished career. Lidstrom for the long haul.