I remember having a discussion with a certain pro-analytics poster, and he was adamant that face-offs were not significant.
I also remember laughing at the absurdity of the claim, and wondering how anyone who follows, or plays hockey could possibly feel that way.
Lies
Damned lies
Statistics
People who don't understand that incomplete data sets yield crap results make me chuckle. Those that vehemently deny that imcomplete data sets yield crap results make me cry.
There is plenty of data showing faceoffs don't have a significant impact on the result in games in the average case over the regular season.
The main reason in the case of a season and facing so many different teams and centers even the best faceoff teams trend towards 50%. For reference, Anaheim was 1st in the league and had only 54.7%, and for the sake of argument Colorado was 2nd with 53.6%. Another reason being some teams are better suited to capitalize on winning faceoffs. Having mobile defense is a big way to help in defense/neutral zone faceoffs and Anaheim has the most mobile defense in the league. In the case of Colorado and teams of that quality, they're simply crap and winning a faceoff gets them no closer to winning the game based on that alone.
In the playoffs its really a different comparison as you face the same team and centers repeatedly and can abuse their tendencies. The ducks have had near 60% faceoffs in all 3 games and their top centers even higher.
What this leads to is the ability to have consistency and reliability in winning a faceoff, which leads to the privilege of being able to have low-risk set plays that the Ducks have been able to employ in a variety of different ways. On the Rakell sensation goal, they wouldn't put Getzlaf lined up as a defender and have a cherry picking Rakell if they aren't really confident Kesler wins the draw against the guy he's been steadily beating all series long. This is an example of faceoffs making a big impact in a way they wouldn't in the regular season.
So its ultimately fair to say faceoffs don't impact the game much over the course of a regular season. But in certain games, certain matchups, on certain teams who are good at faceoffs and good at capitalizing on winning them, it can definitely have a big impact.