The Denver Broncos open 2020 NFL training camp Tuesday at the UC Health Center in Englewood, Colorado. Here's a closer look at a few storylines:

Is Drew Lock ready to be the quarterback of the present, let alone the future?

He'd better be, because the Broncos essentially constructed their entire offseason plan with the idea that he is ready to handle the job -- not only on the field, but off it, too.

Last season as a rookie, the Broncos watched Lock work diligently while spending the first two months of the season on injured reserve with a thumb injury. When he returned to practice in November he showed a far better grasp of the offense than he had in August. Lock took over as the starter in December and went 4-1. During his lone loss -- to the eventual Super Bowl champion Kansas City Chiefs in a snowstorm -- he showed toughness in the pocket as well as when things weren't going well. Those moments of resilience earned him the starting job heading into the 2020 season.

Now he must adjust to what defensive coordinators have waiting for him after having spent the offseason looking for flaws in his game.

After a virtual offseason, can the Broncos expect one of the league's youngest offenses to improve?

The Broncos have pushed all of their chips into the middle of the table hoping it will. When they line up in a three-wide receiver set that includes rookie wide receivers Jerry Jeudy and KJ Hamler to go with rookie center Lloyd Cushenberry III, the average age of the offense will be 24 years old. Left tackle Garett Bolles, 28, will be the oldest projected starter in the group -- he's a month older than right tackle Ja'Wuan James.

The Broncos will be younger, faster and brimming with more potential with the ball than at any point since Peyton Manning retired.

But this is a team that hasn't finished better than 19th in scoring since 2014 and scored 16 or fewer points nine times last season, going 2-7 in those games. There's a lot on Lock's 23-year-old shoulders to be sure, but first-year offensive coordinator Pat Shurmur has promised to let Lock have the freedom to push the ball down the field.

Super Bowl 50 MVP Von Miller is the longest-tenured Bronco and second-oldest player on the team. At 31, what can be expected of Miller this season and beyond?

After a summer of optimism about Vic Fangio's defense a year ago -- and Miller's place in it -- the Broncos didn't have a sack in the first three games. Miller finished with just eight sacks -- his fewest since the injury/suspension-shortened season in 2013 -- and the team's stumbles had Miller saying that losing "defeats my soul."

Bradley Chubb's season-ending knee injury in Week 4 had a significant impact on how opposing offenses handled Miller, and the Broncos' plans in the secondary never materialized after Bryce Callahan's season-ending foot injury in training camp. Five-time Pro Bowler Jurrell Casey's arrival is a potential football life-changer if the 30-year-old Casey plays even to the form of 2019 (44 tackles, five sacks). Chubb's recovery and Casey's presence should give Miller an opportunity to flourish as opposing blockers could potentially have far more problems to solve than they did last season.

Miller has to do his part. Some opposing offensive coordinators believe his frustration got to him and impacted his play, so much so they felt at times if they frustrated him early in games it would dictate the day. Miller has plenty left in the football tank and was already back to work just a couple weeks after season's end. He did battle Covid-19 early in the offseason, but was back at work as spring closed out and is poised for a big year.

Left tackle Garett Bolles has led the league in holding flags in each of his three seasons but has started every game of his career. Do the Broncos believe he will break through, and do they have any other options at the position?

Bolles, the team's first-round pick in the 2017 draft, has been scrutinized almost since the moment the Broncos passed on Ryan Ramczyk -- a first-team All Pro last season -- to select him.

Bolles has indeed led the league in holding penalties in each of his three seasons, including those that were declined. He also finished among the league leaders in penalties overall, but has not missed a game. Elway likes his durability and also believes Bolles showed better work down the stretch. Just two of Bolles' 13 holding flags came in Lock's five starts to close out the season, but the Broncos did not pick up his fifth-year option.

The Broncos made no move, either in free agency or the draft, to crank up the competition for Bolles. The team's best option for in-house competition -- Elijah Wilkinson -- is coming off foot surgery.

How will the Broncos replace perennial Pro Bowler Chris Harris Jr? And what will the defense look like without him?

Harris was a four-time Pro Bowl selection and a thousand-snap staple each year. That kind of versatility and reliability is difficult to find.

Replacing him hinges squarely on Bryce Callahan's surgically repaired foot. Callahan missed all of 2019 and has had two surgeries on the foot since December 2018. If Callahan is indeed the player they believed him to be when they signed him to a $21 million deal (it has since been reworked some) in March 2019, A.J. Bouye's arrival means they have proven starters at cornerback.

But the Broncos will be thin and once again scrambling as they often were week-to-week last season. At least one other cornerback -- De'Vante Bausby, Duke Dawson, Davontae Harris or Isaac Yiadom -- must make a significant jump in play or the Broncos must get some decent work from rookie Michael Ojemudia.