The Cubs had a few big series sweeps early in the season, one against the Dodgers in May and one against the Cardinals in June.
I guess these are better for honorable mention since a season ending well out of the playoffs makes them less important.
May 4, 2021 (game 1 of a doubleheader)
Cubs knock Clayton Kershaw out of the game after just one inning, the shortest outing of his MLB career. Kyle Hendricks pitches a complete game (7 innings) as the Cubs defeat the Dodgers 7-1. Jake Marisnick homers and David Bote drives in 3 runs.
May 4, 2021 (game 2)
In game 2 of a 7 inning doubleheader, the Cubs defeat the Dodgers 4-3 in extra innings (9 innings). Keegan Thompson makes his MLB debut and pitches 3.2 innings to keep the Cubs in the game against 2020 Cy Young award winner, Trevor Bauer. Both teams score 2 runs in the 8th inning, Javier Baez gets the big hit in the 8th inning to tie the game with a 2-run home run. Cubs win it in the ninth on David Bote's walk-off RBI single scoring Kris Bryant.
May 5, 2021
Cubs finish off a sweep of the World Series champions Los Angeles Dodgers with a back and forth comeback victory in 11 innings at Wrigley Field. Both teams scored in the 10th inning and after the Dodgers scored in the top of the 11th inning, Matt Duffy ties the game with an RBI single and Anthony Rizzo wins it with a walk-off RBI single. Rizzo did not even start this game, but batted twice in the game. Cubs defeat the Dodgers 6-5 in 11 innings.
June 11, 2021
Without a doubt, one of the best games of the season. It was called Opening Day 2.0 because it was the first game with full attendance since 2019. Kohl Stewart struggled against the Cardinals and left the game in the 5th inning and the Cardinals took a 5-1 lead. But the Cubs will make a great comeback.
The bottom of the 5th, the Cubs cut the lead to 5-4. The big hit was an RBI triple by Sergio Alcantara, who also scores on an error by Yadier Molina trying to pick him off of third base.
Anthony Rizzo ties the game in the sixth inning with an amazing 14 pitch at bat off Cardinals pitcher, Daniel Ponce Deleon.
Bill Murray's seventh inning stretch was amazing and while he was in the booth, the Cubs took the lead 7-5 on Joc Pederson's 2-run double that nearly cleared the wall for his 2nd home run of the game. Willson Contreras gives the Cubs an insurance run with an 8th inning home run to give the Cubs an 8-5 victory. The Cubs are now 1/2 game in front of the Brewers for first place and are now 4 games ahead of the rival Cardinals.
June 13, 2021
Cubs complete a 3-game sweep of the Cardinals at Wrigley Field. Zach Davies, Ryan Tepera & Craig Kimbrel combine on a 2-hit shutout. Cubs score 2 runs in the 3rd inning when Eric Sogard doubles and scores on a wild pitch. Anthony Rizzo drove in the 2nd run with an RBI single.
Cubs remain tied with the Brewers for the division lead and the loss puts the Cardinals in 4th place in the NL Central, six games behind the Cubs & Brewers.
June 8, 2021
Zach Davies pitches against his former team and shuts out the Padres over six innings. Willson Contreras and Patrick Wisdom homer for the Cubs. It is Wisdom's 8th home run for the Cubs in just 10 starts with the Cubs.