My take is that if we're going to talk about the head-to-head record, then it's worth remembering that Arizona piled up a 17-2 record while ASU was still a teacher's college, and the first ten games were in Tucson. I don't know when we'd say the schools reached a level playing field, but they were tied at 6-6 from the time the Board of Regents took over in Tempe until the time it became a full university in 1958. That was also when Kush took over from Dan Devine: he was then 16-5 against Arizona, and the Sun Devils were 22-11 in their post teacher's college era until Kush was dismissed.
That was separation, in my opinion. They had pulled within 4 games after starting 2-20. But after that, even though ASU continued to be the better program for largely the next two decades, the one thing Arizona was able to do was beat ASU. Full credit to them for that: I was at a lot of those games in the 80s as a kid, and the 9 game winless streak for ASU was brutal.
Since then, I'd say that both programs have underachieved. A three game streak for each, and a few back-to-backs for both. But altogether I feel like it's been a pretty chaotic series to cap off a lot of disappointing seasons. Hey, at least they still have great uniforms...oh wait.