I'm currently facing the same kind of issues, going undefeated for 4-5 games then getting tired and give up one...
Dear Scooby Doo, are you on PS4 ?
I think I played you twice yesterday with my Baltimore Bullets
To maybe answer one of your point, do you have any defensive settings on ?
Have you seen the nice defensive topic ?
here
If so, add me on the PSN (same name as on this forum), I will share you my small tips