Credit to Broodwich, for having this great idea last year. I captured the top 250 players late afternoon on 12/31, prior to the stats getting reset. You can check out the pdf here via Google drive. Have fun charting your stat progress over the last year...
You probably fell off for lack of recent playtime. The ranking only shows "active" players. Not sure how long it takes, but if you haven't logged in for a week or two it will happen. Your rank is restored the next time you join.
Looks like you finished with 27,792 points as of your last session of the year on 12/17/17. That would have been good for 50th place. And you, good sir, finished with 14,664. That would have been good for 177th (this accounts for Woomy).