We know that it's difficult to play a man down, but what exact impact does it have on a team's ability to score and prevent goals? I went through four seasons of English Premier League games and looked at how shot rates changed for the home and away teams when one of their players took a red card or two yellows.
As you can see, when a team is down a man, a team's shot rate drops somewhat (32% for home teams, 13% for visitors) while shots allowed go way up (42% at home, 73% on the road):
| Home | Pct of Time | Shots For | Shots Vs | % of Shots |
| 10-10 | 0.23 | 12.60 | 8.31 | 60.3 |
| 10-11 | 1.71 | 7.35 | 14.67 | 33.4 |
| 11-10 | 2.68 | 15.36 | 7.35 | 67.6 |
| 11-11 | 95.33 | 10.85 | 8.47 | 56.2 |
Both teams control 2/3 of all shots at 11-10. It's also interesting to note that visiting teams spend 56% more team at 10 men than the home team.
So what's the impact on goal-scoring?
| Home | Goals For | Goals Vs | % of Goals | Sh% F | Sh% A |
| 10-10 | 0.80 | 0.54 | 60.0 | 6.38 | 6.45 |
| 10-11 | 0.97 | 1.84 | 34.6 | 13.24 | 12.53 |
| 11-10 | 2.63 | 0.76 | 77.6 | 17.09 | 10.34 |
| 11-11 | 1.40 | 0.99 | 58.6 | 12.89 | 11.66 |
Interestingly, the home team always has a higher shooting percentage, regardless of the game state. When the home team is a man up, they were almost twice as likely to score as at 11-a-side. The impact of the visitors losing a man for half the game is approximately 0.75 goals – roughly the same as giving up a penalty kick – or at least a 30% increase in the home team's expected winning percentage.
