"I think we'll make the commitment to the 4-3," Fox told The Post. "The transition from the 3-4 to 4-3 is much easier than going from the 4-3 to 3-4. So we feel pretty confident about that switch."
The Broncos finished last season last in the NFL in total defense (390.8 yards allowed per game) and scoring defense (29.4 points allowed per game).
The Post also reported that outside linebackers Elvis Dumervil and Robert Ayers likely would resume their natural defensive end roles in the 4-3. The switch could impact how the Broncos use their No. 2 overall pick in April's draft.
"We're working through that with our personnel people, both our pro and college," Fox said.
The Associated Press contributed to this report.