"Player Dismissal and Full Time Results in the UEFA Champions League and Europa League" by Arne De Meyere of Ghent University, Ward Vanruymbeke of Ghent University, and Stijn Baert of Ghent University, Research Foundation – Flanders, University of Antwerp, Université catholique de Louvain, IZA, and IMISCOE: found that red cards for home clubs decrease their goals scored by 0.298 and increase their goals allowed by .399, for a net impact of about 0.7. What surprised me is that red cards have an insignificant affect on away clubs. It says that early red cards hurt away clubs, but away clubs have a goal differential .235 better if they get a red card after the 80th minute. I may look at games on my own to test this. https://www.flashscore.com/football/europe/champions-league-2017-2018/results/ has results from the 2017-2018 Champions League along with indicating red cards, which saves me the time of having to open a page for each game most of which don't have red cards. The authors speculate that home clubs are more likely to expect to be better and try more things, so red cards can hurt their strategy more than away clubs who were going to defend most of the game whether they had 11 men or fewer.