Sixteen weeks into their season, the Broncos are still trying to answer a question that has hovered over them for the better part of two years: Who is their starting quarterback? In the wake of Trevor Siemian’s season-ending shoulder injury, Broncos coach Vance Joseph said Monday he has not decided on the team’s latest starter for Sunday’s game at Washington, D.C. The impending change will be the fourth for the Broncos this year as all three players — Siemian, Brock Osweiler and Paxton Lynch — have taken turns as the starter, backup and inactive quarterback on game days. Lynch is expected to receive some playing time over the next two weeks and Joseph has stressed that giving him another opportunity before the offseason is a priority. But Osweiler, coming off one of the most efficient showings of his career in Denver’s Thursday night win over the Colts, gave the Broncos plenty to mull as they balance talent evaluation with trying to close out the season strong. “Brock played well, so it would be hard to say he didn’t play well. There’s proof in the film there. But we have a lot of things going on as far as the quarterback deal,” Joseph said. “We want to see Paxton play some. That’s the truth. We have to see where he is as a player moving into the offseason. That’s important to our football team moving forward. But we have to discuss it again. We want to make sure he is totally healthy so he can play well if he does play. “Again, Brock did play well. So that’s going to be a discussion that we have to have with our staff today, to kind of figure out what’s best for all parties involved.” Last Friday, Joseph said he would meet with his assistant coaches at the start of this week to decide on their starter for Week 16 and possibly their finale against the Chiefs in Denver, too.