If youre looking to improve ive found what really helps is just like asking people about their thought processes.
One time after having a long as hell argument with this one guy on these forums he challenged me to a 1v1 and i got my rear end handed to me on a silver platter, but the whole time he was explaining to me how he was doing it.
Ive learned to apply a lot of that knowledge since that day.
Moral is, if anybody just flat out destroys you, or does the same to the other team, it rarely hurts to send them an invite, and if they join up you can always ask questions.