For the future, here's an idea: the same nine rounds of a Swiss-system tournament. Let's say we need to select 10 people. We make the top three places automatic qualifiers, and the places from 4 to 17 play tiebreaker matches in a BO3 format: 4-17, 5-16, 6-15, 7-14, 8-13, 9-12, 10-11. At least, in theory, it looks good and doesn't contradict the Swiss-system idea; it just means that three places become automatic qualifiers, and another 14 go into the tiebreaker zone. In theory, this should maintain motivation both for the chasing group – they need to get into the tiebreakers – and at the very top, where there's a fight for the top places.
Added 56 minutes later
Any competition system where there are no elimination games, but there is the possibility of playing to a draw, allows players to agree on the result.