Manning's neck injury resulted in him missing the 2011 season. He had a groin and foot injury that came out after Denver's 2014 playoff loss to Indy.

I think it's debatable if Brees got hurt late in the season last year, cause his collapse in the final month went eerily similar to Peyton's in 2014 and something was not right with his accuracy. I saw the guys from B&G Report on Twitter talk about Brees' throwing motion looking different late in the season from early on and they've debated if he got hurt late in the year.

I made the comparison to Manning's 2014 season cause we were almost a mirror image of that old Broncos team. They had a week 11 loss where their offense only scored 10 points and then would struggle the rest of the year. Denver transitioned from an offensive juggernaut to beating teams with strong defensive play and turnovers. Manning went from MVP candidate in 2014 to his efficiency stats tanking, not unlike how Brees was in the MVP debate until the final month of the season. We had that same transition last year after the Dallas loss.

I have heard from more than one source that Brees suffered a bruise to his throwing hand from hitting a helmet late in the season somewhere around the Cowboys game.

I suspected the same. The injuries that were piling up along the offensive line did not help.
Armstead has already been a little banged up in camp.