The Denver Broncos championship window will fully close whenever future Hall of Fame quarterback Peyton Manning decides to hang up the cleats.  Manning showed signs of declining last year, as his arm looked weaker than usual.

Nonetheless, Denver has more to worry about than just Manning heading into the 2015 campaign.

Who is the primary running back?

In 2013, the Broncos invested a second round pick on Montee Ball. The 24-year-old back showed promise during his rookie year, as he averaged 4.7 yards per carry to go along with four rushing touchdowns.

Heading into last year, Ball was expected to be the man, but things didn’t go as planned. Ball was hindered by a groin injury, which caused him to miss 10 games.

At the time, Ball’s injury seemed to be a major blow, but C.J. Anderson picked up the slack in a major way.

Unlike Ball, Anderson was not highly coveted out of college. In fact, Anderson went undrafted in 2013, but none of that mattered. The 5-foot-8 running back rushed for 849 yards on a 4.7 yards per carry average to go along with 10 touchdowns (two receiving).

The success of Anderson has put Denver’s coaching staff in a tough spot. However, Anderson has the inside track, for now at least.

“He made a big jump as a player, and I think he’s earned the right to walk in to the offseason program — the OTAs — and line up as our starter,” head Coach Gary Kubiak said. “But he’s got to continue to earn it on a daily basis.”

It doesn’t sound like Kubiak feels Anderson will have any trouble getting better.

“I think he’s shown he has all the ability to be an excellent starter in this league, so we’re really looking forward to working with him.”

Don’t expect Ball to go away quietly, however.

“C.J. deserves the No. 1 spot right now. I’m most definitely going to try to work to get it back,” Ball said. “And I believe that I will. I like coming in and being the underdog, just keeping my head down, my mouth shut and just working.”

Whomever wins the starting job, it’s a good thing Denver has quality options.

How much does Peyton have left in the tank?

As mentioned before, there’s legitimate reason to be worried about Peyton Manning moving forward. The five-time MVP didn’t look like his normal self at times last season, especially during Denver’s embarrassing 24-13 loss to Peyton’s former team in the playoffs.

Does this mean it’s over for Manning?

Before we overreact, a lot of quarterbacks would love to rack up 4,727 yards, 39 touchdowns, while hoisting a QB rating over 100.

Manning isn’t in the best quarterback discussion anymore, but he’s still a top five guy at his position today. With Kubiak in control, the savvy veteran must learn some new terminology.

“I’m all in on trying to make any adjustments that I have to and at the same time do some of the things that I’ve done well and hopefully keep doing those well and improve on things I need to improve on,” Manning said.

Realizing the intelligence Manning has, it’s hard to imagine seeing him struggle for long periods of times. Physicality was never his strength, it’s always been his ability to outsmart the opposition.

4-3 to 3-4?

Denver’s defense was one of the best in the league just a season ago. The unit finished 3rd in total defense, allowing only 305.2 yards per game and 22.1 a contest.

This upcoming season, new defensive coordinator, Wade Phillips, wants to see the defense be even more physical. 

“We’re aggressive,” Phillips said. “Defensive players, they’re aggressive by nature. I think you take something away from them when you don’t let them be. And aggressive doesn’t mean blitzing all the time, but it does mean coming off the football — everybody coming off the football. You won’t see a square stance from a defensive lineman, so to speak for people who know football, where you’re reading. This is an attack defense, and that’s the way players like to play. You get the best results out of that and I think you play the best that way so we’ll be that way.’’

Former Broncos defensive coordinator Jack Del Rio used the 3-4 scheme at times based on the situation and opponent. Now, with Phillips running the show, the 3-4 has suddenly turned into Denver’s primary system.

Star linebacker Von Miller doesn’t feel the transition will problematic.

“I think we have guys who can play in lots of spots,” Miller said. “I think you look at the guys we have, we can do a lot of things, we can line up in whatever defense they want us to and make plays.”

In a 3-4 defense, the most vital position is nose tackle. There’s so much pressure on this player to not only flush the passing pocket, but they also are responsible in disrupting the ground game.

Terrance Knighton is no longer in the picture, so it’s time for Sylvester Williams to take on a bigger role.

“This is going to be the most excited I’ve been going into a year, really my entire-two year career,” Williams said. “I’m going into my third year and I’m really excited. There’s a lot of pressure on me, but to be honest, I’m happy to have that pressure. I’m just excited that the coaches really believe in me in giving me a shot to prove myself.”

If Denver is able to get consistent play from their nose tackle, it’ll allow everything else to run smoothly on the back end.

DeMarcus Ware or Shane Ray?

Some may scoff at this question, which is fine, however, this is something Denver’s coaching staff will have to address. Ware is a eight-time Pro Bowler, but it’s clear to see he’s lost a couple of steps.

Phillips is looking to add a more aggressive style of play, which may not suit the soon to be 33-year-old at this stage of his career.

On the other hand, John Elway stole Shane Ray after trading up to take him with the 23rd overall selection in the NFL Draft. If not for a marijuana possession citation, most believe the reigning SEC Defensive Player of the Year would’ve been a top 10 pick.

“We had several people that talked to him,” Broncos general manager Elway said. “He was very remorseful. He realized he made a mistake. He told me it wasn’t going to happen again.”

Barring injury, Ware will be one of the starters, but with Denver converting to a 3-4, there’s sure to be plenty of opportunities for Ray to see action in year one.

The rookie isn’t lacking confidence.

“I can bring whatever they need,” Ray said. “If they need me in the run game, the passing game, helping in coverage, whatever you need me to do, I’m going to go over and beyond to show this team I’m capable of dominating at whatever they need me to do. I’m going to show them that this was the best decision that they could have made.”

At the very least, it’ll be beneficial for Ray to soak in Ware’s knowledge.

Can they protect Peyton?

In 2014, Denver allowed the fewest sacks (17) of any team in the league. The only problem is that Louis Vasquez remains the only starter left from a year ago.

As expected, there’s going to be plenty of open competition along the line.

“I think right now if we went to camp, we have a pretty good idea of how we’re going to line up and go,” Kubiak said. “…I think we know how we’re going to line up: ones and twos and threes, right now. But how it’s going to end up, I don’t know. We’ll see, but it’ll be a very competitive environment throughout.”

Piecing together a good offensive line isn’t an easy task and it doesn’t help when your quarterback has little to no mobility.

Denver used a second round pick on tackle Ty Sambrailo, who doesn’t have time to be a rookie. Four-time Pro Bowler Ryan Clady tore his ACL during practice about two months ago.

Asking a rookie to protect the quarterback’s blind side is a tall task, but Sambrailo seems excited for the possibility.

“There’s no person I’d rather protect,” said the second-round pick. “He’s a great teacher, from what I’ve heard, and being a rookie and coming into a system like this you’re going to want someone like him to teach you how to do it, and how to do it right. So just to have the opportunity to protect a future Hall of Famer is unbelievable and I’m looking forward to it.”

Denver has been knocking on the Super Bowl door ever since Peyton has arrived, but if they want to finally breakthrough and win it all, these five questions must turn into positives.