Something I used to do and have been trying to pick up again, is take notes after each battle. Just short details while the next battle is loading as I don't have time to watch replays often. The problem with my method is that it can be a bit time consuming entering the pertinent data on my spreadsheet. Wotnumbers already has that info plus a lot more done for us!
Having preset or customizeable tags for each battle would keep a running log of brief self reflection on what contributed to successes and failures of the individual and/or team. By filtering a time period and tags, you can identify persistent actions or habits beyond that session. This would also allow you to review trends by wins, losses. performance, map, tank, tank class and more.
Example of some tags might be: cautious - early/mid/late, aggressive - early/mid/late, careless - early/mid/late, overrun, missed opportunity, flexed, held flank, outnumbered, map awareness - good/bad, pushed flank, won/lost flank - returned to base, etc.
By using a combination of tags you can succinctly recap how your battle progressed. Let's say you filter by wins and well above your average WN8; what tags keep popping up for those results? You notice you've been assigning a "YOLO" and "careless - late" tags. OK - I'm probably contributing to the win but getting careless in the late game. I need to be aware that I'm getting aggressive, maybe pushing too hard when I see the battle is in our favor.
Love the app! As a person who does analysis for a living, I'm always keen on using data for improvement. This could be a great avenue for players to refine their habits by quickly logging the self analysis after each battle.