the range of elo the queue will match you with increases over time. to avoid that, you can leave the queue every so often and start it again. that would keep your games in a smaller range around your elo.
That is not really good advice. Because if everyone did that, it would prolong search times for all since matchings in Progress are constantly being aborted.
What you suggest was becoming standard procedure for many in COH1, and created massive Waits untill Relic disabled the editor access and urged players not to abort searches.
Anyway, to the original topic, I think the real problem is just maths.
I have the same experience as the OP allthough I am messing around in the rank of many thousands: a few wins, then opposition quality takes a massive jump for 3 to 5 games. Then back to total newbie opposition and/or teammates.
To me it feels like the matching is simply gearing too much. It should make smaller increments and - without knowing the code - that's probably a question of changing one single ratio.