Well, i don't know if this is the reason, but following my experience:
You will get good players in DC doubles if you have them. I mean, i started my career in 2011, we didn't had any doubles couple, so i played with ''Falla'' doubles (singles player).
In 2013, when Cabal & Farah raised in doubles ranking, they played their doubles, even being +400 & +700 in singles ranking and me being 7th of singles (and Falla TOP50).
Anyway, most of Doubles TOP players (even being bad), would beat TOP singles players in doubles (though, they would get a bagle in singles