The Washington Capitals made a terrible mistake in December of 2019 in trading Chandler Stephenson to the Vegas Golden Knights.
As a result of the trade the Capitals got worse. Yes they still lost in the first round of Stephenson’s second year but that series against the Carolina Hurricanes could’ve gone either way.
That summer Stephenson won an arbitration battle which put the Caps in a salary cap bind ensuing a possible trade. Yes it was good for them in the short term to get out of cap hell but in the long term it was really bad.