OK, you can forget the age explanation. I'm 55 and still getting better every year. The weight gain is a possibility, although I have no direct experience with that. I however DID get a tailbone injury mid-last-season that dogged me for the rest of the season and is still making me a little tentative now (although it doesn't hurt any more). So my money's on the injury screwing with your head.
In retrospect, "Let's get the goat drunk"
should have been my cue to leave the party.