Mark Giordano is the best defenceman in the NHL. There is no issue with this statement. When you're the number one guy on a team expected to be lottery bound only to make the playoffs, leading your team's scoring along the way until a torn bicep falls you, you're the best in the league. And that's without mentioning the fact he's played some of the most difficult minutes in the NHL over that time.
Alas, Giordano did, indeed, get hurt, and missed a quarter of the season. His Calgary Flames did make the playoffs without him, but it wasn't easy on their defence at all, and the team suffered a decline overall. Prior to getting injured, Giordano had 11 goals and 48 points in 61 games, and was running away with the trophy.
You have to think it was going to be his if he'd stayed healthy. Instead, the three Norris finalists are the Montreal Canadiens' PK Subban, the Ottawa Senators' Erik Karlsson, and the Los Angeles Kings' Drew Doughty.
If we're talking points, then Karlsson led the way with 66 over a full 82 games, while Subban had 60 in 82, and Doughty only managed a paltry 46 in 82. So yeah, offensively Doughty couldn't compete with three-quarters of a Giordano.
But the Norris Trophy is, in theory, not supposed to be the "Art Ross but for defencemen" but instead a reflection on the best defenceman in the league. That should take into account how big of a positive impact the player has on his team, and how difficult the circumstances in which he plays are.
Compare Giordano to the three finalists and... well... (via War on Ice):
In terms of having a positive impact on his team compared to other players, only Subban was better than Giordano, with a CF% rel of 6.02, compared to Gio's own 5.74. Karlsson heads things up at 4.47, while Doughty trails at just 1.95. Advantage: Subban, but Giordano is right in the mix.
Then you get into circumstances, and oh, boy, it isn't even remotely close.
As the above graph shows, Giordano played in far more difficult circumstances than any of the finalists. Karlsson and Subban put up a bunch of points, but they did so with the advantage of starting more often in the offensive zone.
When you get to start closer to the opponent's net, there's a better chance you're going to score. Not only was Giordano rarely afforded such a luxury, but he took the bulk of defensive zone starts for his team, still managed to be one of its best players despite his far more difficult circumstances, and still managed to lead them in scoring most of the season.
This isn't to deny Karlsson and Subban as amazing players, just to point out that they had help in ways Giordano did not. Giordano also played against more difficult competition. Probably the only knock you can give him - other than the games missed - is the fact that his partner is TJ Brodie who, in all likelihood, will be a contender for his own Norris one day.
Doughty and Karlsson played massive minutes for their teams, averaging over 20 minutes a game at 5v5 even strength, while Subban and Giordano were closer to 18. That's the only other knock you can give him, but even so: those are still some pretty big, and pretty meaningful, minutes.
When you get down to it, though, at its basest levels: this would have been Giordano's award if he hadn't been hurt, and it wouldn't have been close. He probably would have been a 60+ point player, all the while playing by far the most difficult circumstances of any of the other nominees, and having an incredibly positive impact on his team along the way.
Screw Gio's injury. He should have been a finalist regardless. And maybe he should have won.
He's kind of the best defenceman in the NHL, after all.