Yeah, there can be a bias against those who are playing up. Much of it is based on tennis skill. But some of it is not.
As a captain, I can tell you that I will get an earful if I pair a 3.5 with a 4.0 if the 3.5 isn't up to the job. That means I have to look for 4.0s who are willing to have a partner who is weaker on paper. I also have to find opponents where my gals will have a decent shot. It's a pretty big headache.
That said, I can cut folks a break because I know lots of 3.5s I would rather have as partners instead of some 4.0s.
-- Random Error Generator, Version 4.0
-- Master Moonballer