Change in squadron quality

Just encountered a first in WOFF. I received a message stating that my "poor quality" (Jasta 18) squadron was improving. Upon reaching main campaign screen it is still a "poor" squadron. Is there anything that I do to affect this, or is it that the squadron historically just gets a little better during this time?

I believe it's a function of the quality of the unit's pilots, so as they improve, so goes the squadron. I've seen an "elite" squadron drop to "good" after the death of a couple of aces.