Rather than matchmaking the system is more of a tournament style. It doesn't aim to match similar strength guilds but place teams into brackets. So if you have 3 wins and another guild has 3 wins you're in the same bracket so matching you together is fine. If you lose then you will be matched against other guilds that won 3 and lost 1. Ideally for every team that has 4 wins there are 15 teams with 3 and less. For every 8 wins guild there are 255 guilds with 7 and less.
The goal is to make a ranking of how strong the guilds are and not to provide a fair fight.
If your guild is not strong enough to win more wars in a season then the answer is to make or get in a stronger guild (or get stronger if you yourself are too weak) rather than ask for the system to be adapted to your desires.