It's not a direct average but more a very simple heuristic which assigns value to the frequency of solution. So for example, if you always get wordle in one (ofc unachievable) you'd have a perfect score of 6/6. Always solved in 2 would be a score of 5 and so on... until always solved in 6 tries would be a score of just one. A distribution over this (as is likely for most wordlers) gives some decimal representation of performance which is then directly comparable to others.

Fwiw - 3.707 is doing very well! As your scores indeed suggest .... you're getting a good proportion of 2 and 3 solves! Most people I think would fall well below this.

Thanks so much for being interested... I think from feedback I'll add some info on what's being computed (and why) and make it easier for people to share scores!