#2 Lars Eller in 2016
This was a masterclass of a draft night trade by Brian MacLellan in the summer of 2016 and it was a major reason why they captured the Stanley Cup two years later. Lars Eller was traded from Montreal for two second round picks, one from the 2017 NHL Draft and the other from the 2018 Draft.
He was effective in the bottom six and was a supporting forward anytime someone got hurt. He also gave the Caps depth scoring which was what they needed in that 2018 Stanley Cup run. It also deepened the center core for the foreseeable future at the time.
Eller scored of course the two most important goals in that Stanley Cup run. The first was a Game 3 goal at Columbus and the second was a tiebreaking goal in Game 5 that gave the Caps the lead for good and they would go on to win the Cup.
Last year his time in DC came to an end but now he's qualifying for the Olympics in 2026 for his home country which is a whole lot better than playing for that other team.