While Denver was able to lock up super star Von Miller to a gigantic contract, they weren't able to hang onto all their pieces.
Talented defensive linemen Malik Jackson took off for Jacksonville, which will certainly hurt Denver this upcoming season. Jackson did a strong job in maintaing the line of scrimmage, allowing Miller and Ware to tee off on quarterbacks. Jackson was also the teams second best pass rusher according to ProFootballFocus. I believe this move will hurt them the most as it's unlikely that anyone on this Denver team can match both his size and production, so losing him will likely pay a bit of a price.
What made this Denver defense so great was their awareness and smarts. No one represented that better than Danny Trevathan. He was very effective in both stoping the run and in the pass defense as a line-backer. His athleticism and experience will also be missed very much in Denver.
It was assumed by many that when Peyton Manning retired, Brock Osweiler would take over the quarterback position and hang onto it for years to come, but when he bolted to Houston for a mammoth 100 million dollar contract, suddenly the reigning champs have no trustworthy option at the helm of their offense.
Given the defense this team has and what they will be able to accomplish over the next few years, having a high end quarterback is not necessarily a necessity, but having a reliable one is. Some look at the defense Wade Phillips has built as among the best of all time, so trying to develop a young quarterback who is filled with uncertainty is not how you want to run a team in a prime championship window.
Denver has three options at quarterback heading into camp. They brought in veteran Mark Sanchez, already have Trevor Siemmian on the roster and selected Paxton Lynch in the first round of this years draft. I don't see a franchise quarterback in any of these three names, and believe that the team will severely suffer in the early goings of the season.
While Manning did not have the ability to win games with his arm last year, he certainly was able to do so with his brain as one of the smartest football players to ever strap on a helmet. Take away his knowledge and ability to read defenses and leave you with mere average, inexperienced quarterbacks, Denver will need to rely on their defense far more than ever.