Without going too much into it how do you differenciate a roamer solly from a pocket solly for example? Or you don't? Because if you're only getting information from the logs alone, a roaming solly can have half the kills and dmg of the pocket but be much more on point with bombs and contributing to the team a lot for example.
I definitely think you shouldn't do a global ranking based on logs.tf. For example tf2pickups logs are all named accordingly so it would be easy to filtrate them in order to do a independent ranking for the site for example.
RadmanPart of the point of a skill rating system is so players are punished for not trying (or trolling).
Which is why dota has ranked and non ranked games, altough the non ranked games still have an internal mmr, it's bound to be different as you are not expected to tryhard as you would in ranked matches.