A team has finished a game with 7-21-0 runs-hits-errors line 6 times since 1897, most recently Colorado Rockies on 19 September 2013. That is about one every 73,834 team-games.
Box score for the most recent one ↗
7-19-3 7-20-1 7-20-0 7-20-2 7-21-2 7-21-1 7-21-0 7-22-4 7-22-1 7-22-3 7-22-2 7-23-1 8-1-0
The whole distribution — Runs-Hits-Errors Lines · All 18 shapes