Biggest 'new' positional holes

The Pittsburgh Steelers will miss Le'Veon Bell while he's injured. Geoff Burke/USA TODAY Sports

The NFL is a rough league. Coaches and general managers spend the entire offseason making changes to their rosters and envisioning what a great array of talent they will assemble for Week 1. But as we have seen this offseason, injuries occur and quickly derail those well laid-out plans. One of the greatest challenges for NFL franchises is adapting to injuries to key players and still finding ways to win games on a weekly basis.

Below are five positional group holes that weren't necessarily a problem before the preseason, but now need to be addressed.

Pittsburgh Steelers: Running back

Due to a change in scheme, poor blocking (mostly from injuries to the offensive line) and just poor running back play, the Steelers really struggled to run the ball effectively last season and got very few big plays from their ground attack. The line is young, talented (healthy for now) and in its second season in Todd Haley's offense, although the Steelers are switching to a movement-based zone-blocking scheme from their traditional power downhill attack. But this line is athletic and capable of making the switch.

To remedy the running back problem, Pittsburgh drafted Le'Veon Bell in the second round. Bell is a big back in the traditional Steelers mold, but also an adept zone-blocking runner who catches the ball very well -- something Haley requires from the position. Bell was drawing rave reviews in training camp and it appeared as though Pittsburgh had its true feature back. But Bell's preseason foot injury has put a huge damper on those expectations, and mid-foot injuries like his can linger. That leaves last season's incumbents, Jonathan Dwyer and Isaac Redman, competing for the lead job -- which is exactly what the Steelers didn't want in the first place.

Dwyer has slimmed down and looks noticeably quicker, while Redman offers more in the passing game, but neither is overly dynamic. The Steelers did trade for Felix Jones, whose stock has plummeted greatly since his best days in Dallas, and signed LaRod Stephens-Howling in the offseason. Stephens-Howling was effective in the first preseason game, but hasn't seen time since due to injury. Expect him to garner some carries and receptions on a weekly basis, especially while Bell is sidelined.

Ben Roethlisberger has been terrific this preseason. He is going to have to keep it up for the Steelers to keep moving the ball on offense, especially early in the season.

Oakland Raiders: Offensive line

The Raiders have a roster that is ill-equipped to handle a major injury to one of their top players, so when left tackle Jared Veldheer partially tore his triceps during the preseason and went on IR, it was a big blow. He will miss a significant portion of the season, and the strength of that arm will be a question mark when he does return. The Raiders used a second-round pick this year on the extremely talented but extremely raw Menelik Watson, with the intentions of slowly developing him to pair with Veldheer. That would give the Raiders a pair of athletic bookends to anchor their line for years to go, along with Stefen Wisniewski, a building-block player at center.