He missed those kicks because of the emergency long snapper who could not get off a good snap to save his life that game.
There was a story about this I feel like recently that was a good read.
View: https://www.youtube.com/watch?v=c6OKT-FA6lI
I just re-watched his kicks. The first miss (at 8:10 of the video above), the snap wasn't perfect, but was easily handled by Walter, the holder, who got it down perfectly and in easy time for Vinatieri, who just pushed a 31-yarder to the right. Totally on AV.
Second miss (40:39 of the video above), the snap was very good. Easily handled by Walter, perfect hold and place, and Vinatieri just didn't get any elevation on the kick. Nothing wrong with either snap or either hold. Both totally on AV. (and the blocking wasn't good either)
I mean, I heard the same story you did, but you can watch the kicks right there in the video above.