i'm the guy who played cindysphinx's team the other night. we played #3 and won 6-3, 6-3.
i'm a recent bump up to 4.5 and with the exception of a pretty decent serve - i'm a very low end 4.5. my partner on the other hand is a 3.5 lady who is very tall and likes to rush the net. she could easily play 4.0 women's league.
our opponents were a 4.0 guy who was low to mid level 4.0 in my estimation. some solid groundstrokes and serve but very inconsistent and volleys were not a strength. his 4.0 partner was a low to mid level gal with lots of trickery and deception and good touch but very little power.
not a humble brag but my partner and i were not playing our best game - a lot of that was our opponents frustrating us with the guy giving us not exactly textbook shots and the girl giving us a lot of softball, moonball, slow speed stuff. but at no point did we feel we didn't have the match in hand.
my partner easily hit 75% or more of the shots with our opponents hitting as much as possible to her. to counter that we did a lot of planned and unplanned poaching. or i sat back at the baseline and waited for a lob to go over my partner's head and try and take a point over again from there.
and if it makes cindy feel any better, my teammate on court #2 is a very strong 4.5 (sadly not the strongest i've seen but he's up there) and he pretty much toys with me too when we practice. i think that's the circle of life.