After NaVorro Bowman told Sports Illustrated that it takes him two hours to get his surgically repaired left knee ready for practice, former NFL safety Rodney Harrison opined on NBCSN this week that such a lengthy warm-up could indicate the 49ers’ inside linebacker was returning to the field too early. “I didn’t have to warm up my knee prior to the knee injury,” Bowman said. [...] I have to make sure I’m able to do everything I have to do when practice starts. The players weren’t the only ones working together during the joint practices between the 49ers and Broncos this week. Elway said he and Baalke are friends and the conversation was mostly personal, but suggested some trade discussions arose. Inside linebacker Nick Moody (knee) and cornerback Tramaine Brock (pulled leg muscle) both left practice. Head coach Jim Tomsula indicated neither injury was serious. Eric Branch is a San Francisco Chronicle staff writer.