I really don't know why, but in doubles my game is always on, and I rarely feel tight or get nervous. I just go out there and play my game. Singles it's a whole different story though. The biggest area where I notice this is in my returns. I don't do that well in singles but in doubles I just feel like I can rip my returns no matter what the serve. Basically my game is always on a higher level in doubles than singles and I can never figure out why. It's not like I have a specifically doubles friendly game either. I'm really a baseliner with decent volleys, and a big serve so I'm not asking why I'm better at doubles, I just don't play like how I do in practice in singles as much.