Bryce Harper, 2018-19 offseason
Not only did the Yankees pass on Harper, a lifelong Mickey Mantle fan who would've died to bring titles to the Bronx, but they boasted while they did it about how special and unique it made them.
Rest assured, if Harper ever gets the chance to face the Yankees in the World Series (he won't, the Yanks are dead ducks), he will destroy them. He will make Brian Cashman wish he'd never been born, grown hair and lost it.
Harper's free agency will forever be the darkest stain on Cashman/Steinbrenner's resumé. The Yankees' head honcho took a perverse type of bizarre joy in removing himself from the Harper race that winter, stating that New York had "six" outfielders and didn't have any interest in playing the eventual Phillie at first base (something he's doing quite well in 2023, as a matter of fact!).
Counterpoint: Who cares?
Instead of being "predictable" and signing the best player available to a deal that looks like pennies on the dollar these days ($25.38 million AAV, God forbid), the Yankees took the field with their six outfielders, had to acquire six more due to injuries, exiled Giancarlo Stanton to the DH pile, and never hit their ceiling before everything fell apart.
When Stanton fell into Cashman's lap prior to the 2018 season, he should've looked at the move as a prelude to going full Death Star the next offseason and adding Harper, too. Instead, he let it halt his team's progress, then boasted about how disinterested he really was in the future Hall of Famer. Disastrous on a whole 'nother level from the rest of these numbskull calls.