Over the last 50 years or so, I've formed the opinion that when an opera star starts performing in the pops arena it's almost an admission that he's about over the hill for the big opera leagues. Lauritz Melchior, Feruccio Tagliavini, and Ezzio Pinza come immediately to mind. For the pop market they still have what can be great voices, but they step down to that less demanding market.
May well be true here with Pavarotti, too.

Dave Oesterreich