Does this phrase even make sense? To say that a particular approach "achieved, on average, mixed results at best."

How can this actually be interpreted to have a definite and specific meaning? Or is that impossible?

(The phrase comes from an article I'm reading about Dev-Ops.)

Does this phrase even make sense? To say that

[a particular approach] "achieved, on average, mixed results at best".

I'm concerned about the combination of 'on average', 'mixed results', and 'at best': does it make sense to use two (never mind three) of these together like this?

(The phrase comes from a DevOps article by Damon Edwards.)