While Pavarotti and his two sidekick tenors have been turning opera into a mass-appeal juggernaut, Bartoli has been trying to shrink a bloated genre.
Bartoli feels that opera is a bloated genre. 
mnli hypothesis: Bartoli feels that opera is a bloated genre.  premise: While Pavarotti and his two sidekick tenors have been turning opera into a mass-appeal juggernaut, Bartoli has been trying to shrink a bloated genre.