Clady sustained a torn ACL in Wednesday's practice, and his season officially ended Friday when the Broncos officially placed him on their injured reserve list.
Once viewed as the best young player at his position, Clady was a two-time first-team All Pro by the time he was 26 years old. But he has struggled with injuries, from a torn patella tendon in 2010 to the Lisfranc fracture in 2013. Clady is due $9.5 million next season as part of the five-year, $52.5 million contract he signed in 2013.
Where the injury hurts the Broncos most is in depth and continuity, as the offense transitions to new coach Gary Kubiak's zone-blocking scheme.
Second-round pick Ty Sambrailo got the first crack at left tackle in Thursday's practice, with Clark remaining on the right side.
"Ty's a very athletic young man. That's a lot to ask of a very young player, but we've got a good month here of work," Kubiak said of the rookie. "We felt like, when we drafted Ty, he was athletic enough to play on both sides."
Kubiak still needs to settle on a starter at left guard and center as well, which means he could have four new starters on his reshuffled offensive line.
That lack of familiarity up front is a concern for an aging quarterback who had trouble escaping pressure down the stretch last season.