It’s hard to call the Bulls’ embarrassing loss Friday to the Hornets rock bottom for their front office, especially when the floor continues sinking. It’s no secret executive vice president of basketball operations Arturas Karnisovas has been actively shopping veterans Zach LaVine and Nikola Vucevic since the summer, hoping to acquire draft assets and build a better future. But now it’s becoming clear that even some pieces the Bulls were counting on to be part of that future are looking more suspect than prospect. A source Saturday told the Sun-Times that Karnisovas finally has bought in to the idea that 23-year-old forward Patrick Williams needs a change of scenery, opening the door for him to be on the trade block, too.