In my guillotine league I made it to the final week, week 16, so it had gone from a 17-team league to a 2-team league at that point. I blew most of my blind bid dollars early in the season so my opponent had a truly stacked roster even for a 2-team league. My team was comparatively weak but I had managed to outscore him in week 15 for the first time in well over a month with good free agent pickups that had good matchups. (Marvin Jones 27 points, Brandon Aiyuk 22 points, Ryan Tannehill 43 points.)
My worst move was in week 16 I went to the FA well too many times, and out-thought myself trying to cut players I wasn't sure I wanted to start so I would have flexibility as the week went on. Remember there games at 4 different times Friday and Saturday. First was Vikings/Saints, I strongly considered picking up Irv Smith (26 points), but didn't, I also cut Adam Thielen (23 points). Next was Bucs/Lions. I cut Mike Evans and started Marvin Jones again. (-40 points), partly because I decided to start Leonard Fournette (15 points) and didn't want two non-QB Tampa players, but despite my confidence in Tampa's offense I didn't pick up Brady (34 points, 14 more than my other QB starters). Then 49ers/Cardinals, I'd been rolling with Kenyan Drake, but cut him, he only scored 13 but better than what I ended up with. Then Dolphins/Raiders, I really felt like Gaskin (38 points) could thrash the Raiders defense but didn't pick him up in part because he was coming off injury and in part because, not having started Irv Smith, I'd decided to roll with Mike Gesicki (11 points) and I didn't want two Dolphins.
Then on Sunday because I was down by so much (opponent had Kamara, among other things), I decided to start Sammy Watkins and hope for one of his miracle big games since I had Mahomes and my opponent had Kelce and Hill. Of course Kelce and Hill got all the action that day, Watkins barely managed 4 points.
So that whole weekend was one long string of bad decisions. Lost by 99 points to a team I had outscored the week before.