The quality of the geniuses, in my experience, has been going down for a decade.
Agreed, however Apple really hit the sweet spot on a lot of Genius hiring from 2005 to about 2012 or so. The recession was in FULL swing by late 2007 (but college grads were finding new jobs harder to come by quite a bit earlier) and there were A LOT of two camps: young technically able or technically capable computer science/engineering/tech grads that had no other job prospects in their real industry, and middle-aged tech folks who had be laid off.
The combination worked out perfectly for Apple and they had a TON of openings and need for Geniuses and Apple paid, for retail, really well. Over time though, those people found non-retail jobs that paid A LOT more and had normal hours, founded their own local support companies (I know several of these) and the replacements, either drawn from Apple's sales teams or from outside, just haven't been the same quality since college grads now get hired, and many of the older ones have moved to retirement age or close to it.
Johnson leaving and Ahrendts absolutely gutting what made Apple Retail work didn't help.