Like so many others, Michael Schiavello has learned that dependability and availability aren’t among Nick Diaz ‘s strong suits. The veteran broadcaster took to Twitter on Monday night to scold the recent UFC title challenger for skipping a taping of his “The Voice Versus” interview series. As he wrote: “@nickdiaz209 has no showed The Voice Versus. Nick you have let your fans down again… And me a big fan in particular. Unprofessional mate.” Over the weekend Schiavello confirmed Diaz was scheduled as a guest, and he said was flying to the fighter’s hometown of Stockton, Calif., to tape the show, which airs on AXS TV. The show previously has drawn many notables from the MMA and entertainment industries, including Dana White, Alistair Overeem , Steven Austin, George Foreman and Steven Seagal. Diaz, though, apparently won’t be one of them