The scoring system appears to be like hockey.
2 points for a win.
1 point for a tie.
0 points for a loss.
These are qualifying points. They will determine your tier. (Who did FIRST hire that likes tiers?)
The ranking score is the average of the losers score in all the matches you have played. Consider this the first tiebreaker of the tier.
The highest match score is the second tiebreaker, and a coin toss is the final tiebreaker.
So win-loss-tie record determines ranking, then the tiebreakers sort them more. Average of the losers score is the first, followed by the highest match score.
As for defense, there is plenty of defense you can do.
Wetzel