It sounds familiar to me, but I can’t think of where I came across it. Are you putting this question to the Jazz Research listserv? Decent chance that someone there might know the answer. I can also post your query to the Ellington Facebook group I’m in, unless you’d for any reason prefer that I not.
This quote pops up a lot through Google searching, but I can’t yet find a solid source for attribution. Is it the one of which you’re thinking?
"If you have a great band with a mediocre drummer, you have a mediocre band. If you have a mediocre band with a great drummer, you have a great band!"