The Pittsburgh Steelers have plenty of depth in their defensive front seven, but even with most starters settled at those positions, there is room for some players to move up the depth chart. 

Robert Spillane made a case for more playing time in 2020 when Devin Bush was lost for the season. The two could be in direct competition throughout training camp.

If Spillane impresses as much as he did last season, he could even start alongside Bush on the inside of the linebacker unit with T.J. Watt and Alex Highsmith flanking them. 

Pittsburgh has more questions to answer at defensive back, where it needs to replace Steven Nelson and Mike Hilton.

Joe Haden is the veteran in the cornerback group, but outside of him, there seems to be an open competition for a starting space. 

A handful of players will have a chance to rise up the depth chart in August to take hold of a starting role. 

Robert Spillane

Spillane made an immediate impact when he was slotted into the starting lineup in 2020. 

He produced 45 tackles, four tackles for loss and three quarterback hits over 12 games. Most of those totals came from his seven starts. 

Spillane suffered an injury himself in December, so he only gave the coaching staff a half-season sample size to prove what he could do in an expanded role. 

With Bush back in 2021, Spillane will compete with the former first-round pick and Vince Williams for time at inside linebacker. 

Williams was Pittsburgh's second-leading tackler in 2020, and he chipped in three sacks behind Watt and the other edge-rushers that made up the bulk of the team's sacks. 

Spillane might not supplant Bush and Williams, but he can earn more snaps as the first linebacker off the sidelines if he turns his 2020 form into a solid camp. 

If he takes another step forward, Spillane could help make Pittsburgh's front seven even more tenacious than it was in 2020, which would be a boost heading into a difficult AFC North slate. 

Cameron Sutton

Pittsburgh's defensive back competition will be closely watched throughout training camp.

Haden should be locked into one starting position in the secondary, so there should be an open competition for the spot opposite him on the gridiron.

Cameron Sutton could grab hold of the second starting position and help the Steelers through a seamless transition from Nelson and Hilton.

NFL.com's Adam Rank dubbed Sutton as the team's breakout star for the 2021 campaign. 

"Sutton is expected to be a starting cornerback for Pittsburgh this season," Rank wrote. "Fulfilling an annual tradition of the Steelers, where they lose some stud and yet somehow have a more-than-capable replacement waiting in the wings. Like the way they find no shortage of people to play Batman." 

The 26-year-old made six starts in 2020, but he still needs to prove in camp that Mike Tomlin and the coaching staff can trust him as an every-down player. 

Sutton has not had more than one interception in a single season during his three-year career, and he gave up 11.9 yards per completion in 2020.

If he shows that he can improve on those totals to be a solid complement to Haden and safety Minkah Fitzpatrick, he could take the starting role and not give it up.

Pat Freiermuth

Most of the buzz surrounding an offensive rookie will revolve around running back Najee Harris. 

Harris is expected to be the primary ball-carrier to replace James Conner, but he is not the only offensive rookie who can make a difference in 2021. 

Second-round pick Pat Freiermuth had 16 touchdown catches over three seasons at Penn State, and he could make a run for Eric Ebron's snap count in 2021.

Ebron had 558 receiving yards and five touchdowns in 2020. He was fourth on the team in both categories. 

If Freiermuth turns in a strong camp, Pittsburgh could feel more confident going with a two tight end approach, which may cut into some of Ebron's totals. 

Ben Roethlisberger still has to spread the ball around to JuJu Smith-Schuster, Diontae Johnson, Chase Claypool and James Washington. Adding a sixth option to the passing game will not hurt, but it could also take some totals away from the veteran players.

Freiermuth could be best used in the red zone since he had 15 touchdowns in his first two seasons in the Big Ten.

If he makes an impact across the middle, Freiermuth could give the Steelers a more well-rounded offense that will be required to beat divisional rivals Baltimore and Cleveland. 

Statistics obtained from Pro Football Reference.