he Buffalo Bills are returning the vast majority of key players from last season's 10-6 club that was good enough for the No. 5 seed in the AFC playoffs, and with a handful of new pieces added to the roster, the training camp competitions at certain spots will be fierce. Coach Sean McDermott has more depth at his disposal than in any of his first three seasons in Buffalo. 

And most of the Bills' free-agent signings from a few months ago have ties to McDermott's successful tenure with the Panthers, which makes things even more compelling. Let's explore the five most vital and riveting training camp competitions leading into the regular season.

1. No. 2 cornerback

The Bills will have their All-Pro cornerback Tre'Davious White on one side of the field this season, after he decided to opt in on deadline day. Across from him? No one's quite sure who that'll be right now. It's the most important and interesting training camp battle for Buffalo. 

Levi Wallace is the incumbent, basically. He had an fine rookie season in 2018 after going undrafted and began the 2019 season as the No. 2 corner. Although he broke up nine passes and snagged two picks, after a few games with uninspiring play midway through the season, Bills coaches decided to rotate Wallace and veteran Kevin Johnson -- who's now on the Browns. Wallace has to play more consistently to hang onto the job. And the Bills made a low-risk, potentially high-reward cornerback signing when Josh Norman was inked to a one-year deal in March. Of course, Norman rose to stardom in Carolina in McDermott's defense but is now 31 years old coming off a career-worst season in 2019. These two will battle it out and play a decently large role in deciding the ceiling for Buffalo's high-end defense. 

2. Second-string edge rusher

Jerry Hughes and Mario Addison will be Buffalo's top edge-rushing unit. Behind them, it's not so clear. Trent Murphy, now entering his third season with the Bills, is there, and while he's mostly been a disappointment as a free-agent acquisition, he did have five sacks in the final eight regular season games in 2019. 

His job won't be handed to him as the first rotational edge, although the unusual offseason will help Murphy start there when the season begins because his main competition is rookie A.J. Epenesa. The powerful and polished second-round pick will be moved around the defensive line, but he'll mainly rush around the outside. The long shot in this competition is last year's seventh-round pick Darryl Williams, who shined in the preseason and plays with a nice collection of pass-rushing moves and strength at 6-6 and over 250 pounds.