The Broncos wave goodbye to quarterback Peyton Manning on Monday. Will they say hello to the Brock Osweiler era soon after?

Free agency opens at 10 a.m. with teams permitted to negotiate contracts with the agents of free agents, though no player can officially sign until 2 p.m. Wednesday. The Broncos extended Osweiler a three-year, $39 million offer but have been unable to reach an accord. Deadlines spur action, so talks could begin to percolate Monday.

It is difficult to assign Osweiler’s value.

Los Angeles Rams quarterback Nick Foles, a loose comparable in Osweiler talks, received $13.792 million guaranteed last year on a two-year deal. However, Philadelphia’s Sam Bradford landed $22 million guaranteed on a two-year contract last week, hinting of the limited free-agent options. Bradford has 63 starts, compared with Osweiler’s seven, but he owns a 25-37-1 record with no playoff appearances.

Osweiler, 25, can test free agency before making a decision. Multiple clubs feature quarterback vacancies or are seeking upgrades, most notably Houston, Los Angeles, Cleveland, San Francisco and the New York Jets.

When free agency begins Monday, the vault is expected to open for Broncos defensive end Malik Jackson and inside linebacker Danny Trevathan. The Broncos made a multiyear offer of about $11 million per season to Jackson, which has not been enough to persuade him from testing the market. Jacksonville is most mentioned as a favorite to land Jackson because of its available space under the salary cap. Considered by many to be the NFL’s top available overall free agent, Jackson has been seeking $14 million to $15 million per season with a guarantee greater than San Diego’s Cory Liuget’s of $30.477 million. The Chicago Bears and Oakland Raiders are potential fits.

Trevathan predicted last month the Chicago Bears would court him aggressively in free agency. They are considered the front-runners, followed by Atlanta and Miami, both of whom employ coaches with ties to the Broncos.

The Broncos are working on multiple fronts, attempting to create more salary cap room through restructures for offensive tackle Ryan Clady and outside linebacker DeMarcus Ware. Clady has told teammates he expects to be back. Ware is among the most popular players in the locker room and finished the postseason strong.

Offensive guard Louis Vasquez, who struggled last year because of injuries, is another candidate to receive a pay cut.

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