As far as the handwaving of Corsi for the sake of Corsi, IMO it's because team's don't play to maximize their Corsi. The assumption (which I think is reasonable) is that a player won't just throw the puck away all the time, team's try to make scoring chances so it still works as a stat. Corsi has more utility as a team stat, it's not really fair to penalize a team's shutdown line for playing against the best players, and most people control for this. I don't agree that it's applied to all players evenly because good analysis uses QoC, zone starts, TOI, and other controls. Nobody worth listening to uses raw corsi to evaluate players. The other aspect is that it's the sum of all 5 players on the ice and the corsi events for and against. If a shutdown D lets a puck mover freewheel, it will show up in his corsi because he's on the ice while it's happening.
I think this is a very interesting part of the whole debate. I guess the question we need to ask is whether or not different styles of play are equal, is a top tier shutdown D equivalent to a top tier puck mover? I guess for me my view of the game is that the best defense is a good offense. If a guy's skillset is to keep shots to the outside it might lower the chances of a corsi event becoming a goal, but it drastically reduces the likelihood of his own team recording corsi events or shots (and goals).
We can look at the Karlsson vs Weber or Suter vs. Subban debates here, it's just hard to find that point where we're overvaluing a player's skill in his own zone over a player's ability to not be there in the first place. I think intuitively we all understand that a defenseman bringing offense is the better player (no matter how good Vlasic is defensively he won't be in the Norris talks) but the challenge comes from comparing guys at the lower end of the scale, the Gleason vs. Liles trade in Toronto comes to mind.
