*disclaimer* this Is speculation based on my own case.
I got a LoA this year, dated Aug 31. I only have one year of sports, JV wrestling, but I have strong test scores, a ton of AP courses, a high GPA and class rank, and good leadership positions that provided me material for my essays. I truly think I got mine almost solely because of strong academics and ECs. I will never know what it was in my file that stood out to WP, but from what I understand, something has to pop out in a major way, especially with acceptances down and applications up.
However, do NOT expect one. I was hopeful, but never dreamed it'd happen. I remover not being able to speak because I yelled and screamed so much when I read the letter. Surprises are definitely best.