Would meniscus surgery be an IR event under normal circumstances? I had surgery on my meniscus for a tear after my original knee surgery didn't heal properly(long story), but after about a month I was back to 100% normal...

Could it be Byrd's lack of production influenced Payton?

Sounds like he don't play unless he's "100%"
Jairus Byrd won’t play unless he feels 100 percent | ProFootballTalk

Byrd hasn’t been in the lineup at all for the Bills this year because of his own foot problem and, unlike Holmes, Byrd won’t be taking a step on the field until he’s certain that he’s 100 percent.

That's a whole nother injury and I have no idea how serious his foot injury was...

Plantar fasciitis is a common painful disorder affecting the heel and underside of the foot. It is a disorder of the insertion site of ligament on the bone and is characterized by scarring, inflammation, or structural breakdown of the foot's plantar fascia. It is often caused by overuse injury of the plantar fascia, increases in exercise, weight or age. Though plantar fasciitis was originally thought to be an inflammatory process, newer studies have demonstrated structural changes more consistent with a degenerative process. As a result of this new observation, many in the academic community have stated the condition should be renamed plantar fasciosis.[1]

Plantar fasciitis is the most common injury of the plantar fascia[2] and is the most common cause of heel pain.[3][4] Approximately 10% of people have plantar fasciitis at some point during their lifetime.[5][6] It is commonly associated with long periods of standing and is much more prevalent in individuals with excessive inward rolling of the foot, which is seen with flat feet.

Not just flat feet



https://en.wikipedia.org/wiki/Plantar_fasciitis