AZGOP has a horrible bench.
Is this really it? The most prominent AZ Republicans tend to be weak statewide candidates, but there are still plenty of AZ Republicans who could be much more popular than McSally if they could be persuaded to run and don't seem to have categorically ruled out bids.
I've mentioned former Governor Jan Brewer who was actually a meaningfully moderate Republican on certain issues as opposed to a "moderate [polite, but very right wing] Republican" (she supported Medicaid expansion to protect rural hospitals!). Even if one rules her out, all of the current row officers besides Ducey would also probably be doing better (although there is the issue of whether any would have been willing to accept the Senate appointment). Surely, some recent former row officers/Representatives would also have been better bets, although a few of those lost their last primaries.