I think your problem is you need to skip lower point battles. Your team should be capable of a score of 4830+ which is competitive for Top 1000. The arena match up system gives out a wide range of opponents with a tendency to give opponents on the lower end. If you only fought the 690+ teams, your score would be higher. However, you'll likely have to spend a lot of dueling swords to keep rerolling for high point match ups. I have a friend with only 2 merge levels that is in the 4830 range. If you have 8, you should be able to go even higher.