LAS VEGAS -- Raiders quarterback Gardner Minshew suffered a season-ending broken collarbone late in Las Vegas' 29-19 loss to the Denver Broncos on Sunday, a source confirmed to ESPN's Adam Schefter. Minshew, signed in March to a two-year, $25 million contract with $15 million guaranteed, was injured on a fourth-quarter sack by Broncos linebacker Cody Barton.  Minshew landed awkwardly on his left shoulder and appeared to be fighting back tears as he exited the field holding his left arm in a curled position. He went straight to the locker room with a trainer. "It doesn't look good," Raiders coach Antonio Pierce said after Las Vegas dropped its seventh straight game to fall to 2-9.  With Minshew out, the Raiders are left at quarterback with Desmond Ridder, signed off the Arizona Cardinals practice squad Oct. 22;  Aidan O'Connell, now eligible to come off injured reserve after suffering a broken thumb on his right...