Do the Kentuckians just like it that Mitch has been in office for a long time and gets national attention for the state? Supposedly, that is the case for McPain of AZ.
Honestly, I think it is no more complicated than two factors. McConnell has a well financed and very powerful organization here. His people rule the Kentucky GOP. And the majority of voters are lemmings and can be counted on to vote for a long standing incumbent nearly all the time.
I can tell you that the material in my mailbox from McConnell's side during the primary campaign when Bevin was running against him for senator was down & dirty, lots of it, and none of it cheap to print. Ditto for other media.
His people tried the same thing to keep Bevin from winning the primary for governor. IMO, McConnell and his people running the GOP are despicable oxygen wasters.