DeepThe real way to improve is to join a team. Ask to join a low/mid Open team with a strong leader, and you will learn your role and aim/movement very quickly. Pugs are horrible for practice, because nobody there is really concerned about playing as a team a majority of the time.
Deep I haven't played a pug with you in a long time but from what I've heard you're the one not being a team player and going for market gardner frags to post on your YouTube channel. Even in Tf2mix pretty much everybody is trying to play as a team. Sure, the coordination isn't the best and there's going to be times where your scouts forgot to cap mid but for the most part people are playing together. I know that I personally will do whatever it takes to help my team out, whether it's farming cap points, building uber, sucking it up and going heavy, or sacrificing myself onto the point.
From what I've noticed, once one person starts being silly in a pug everyone else joins in unless the first person quits fucking around within a couple minutes. Deep, I wouldn't be surprised if you're the guy thats always the first one to pull out the folding spade that crits while airborne in pugs.
You're right about pugs not being as good for practice as scrims but they're definitely not horrible.