Coach Gary Kubiak reacted calmly last week when asked about the Broncos quarterback uncertainty. He wants to add a player to compete with Mark Sanchez. Denver continues to cast a wide net in its search but there could be a catch in any trade pursuit of San Francisco’s Colin Kaepernick.

His $11.9 million salary guarantees Friday, creating a potential deadline to trade or release him. But surgeries over the past five months on his left shoulder, left knee and right thumb make it possible Kaepernick’s salary would already be guaranteed because he would be unable to pass a physical by Friday, according to Pro Football Talk.

CBS Sports’ Joel Corry, a former agent, agreed Monday that releasing Kaepernick might be complicated due to his injury history. The 49ers could argue Kaepernick’s injury only applies if he’s unable to play when the regular season begins in September. The players union could counter that it applies whenever he’s released.

Even if the 49ers exercise Kaepernick’s contract, it wouldn’t preclude trading him at a later date . But, it could push a move closer to the NFL draft on April 28-30 in Chicago than the end of this week.

Broncos general manager John Elway insists he’s prepared to look at all options to add a quarterback for as long as it takes. The acquisition of Sanchez, a veteran with starting experience, has allowed Denver to proceed at its own pace. They have expressed interest in free agent Ryan Fitzpatrick, and have been mentioned as a possible trade candidate for Tampa Bay’s Mike Glennon, Houston’s Brian Hoyer and Cleveland’s Josh McCown.

“It’s a fluid situation. John and I talk about it every day. I think obviously we know the guys out there that are still free (agents). There is no secret there. There are not many of those. The draft this year has some good quarterbacks in it. It’s a day-to-day process and something that we continue to work through,” Kubiak said. “Whoever we bring in, it’s about competition. We’re not going to give anybody a job. We’ve got a good football team. Whoever comes in and plays that position for us is going to have to earn it.”

First-year San Francisco coach Chip Kelly indicated last week that he wants Kaepernick to stay, saying, “You don’t cut talent.” The 49ers benched Kaepernick last season, replacing him with Blaine Gabbert.

Troy E. Renck: trenck@denverpost.com or @troyrenck