The Gophers blamed Mitch Leidner's shaky 2014 debut on nerves and his exuberance, a plausible explanation given all the different circumstances that night.

It was the season opener and Leidner's first game as the unquestioned starter. The Eastern Illinois game represented his first true moment in the quarterback spotlight. We bought the premise that he was overly excited and felt like he had something to prove.

But now? The concern level jumped a few notches on a postcard Saturday at TCF Bank Stadium.

Leidner continued to misfire wildly on passes and then suffered a knee injury in the fourth quarter of a 35-24 victory over Middle Tennessee State.

Leidner completed only five of 11 passes for 67 yards with one touchdown and one interception. He was 0-for-2 in the second half.

He left the game after a defender crashed into his knee and was scheduled to have an MRI, according to coach Jerry Kill, who expressed concern. The Gophers might be forced to start redshirt freshman Chris Streveler on the road against TCU next week.

Even if Leidner's injury is not serious, concerns about the passing game linger like a smudge mark. An area of emphasis before the season, the Gophers passing game has been virtually nonexistent in a pair of victories against weaker opponents.

Progress is hard to find.

"There's no question that we've got to continue to work throwing the football and continue to get better," Kill said.

Kill accepted some of the blame for an ineffective passing game, saying he became too conservative in the second half. Armed with a comfortable lead, Kill said he didn't want to risk an interception, especially with Middle Tennessee's safeties playing deep.

The Blue Raiders had no answer for the bullish running of David Cobb, so the Gophers were content to keep pounding away on the ground.

That's fine, but eventually the Gophers must establish some semblance of a credible passing game, if they want to succeed in taking another step in building their program. They can't continue to be so one-dimensional.

The Gophers can handle Eastern Illinois and Middle Tennessee with their running game. That won't suffice against stiffer competition.

"We work every day [on passing] and I think it comes with confidence and what the defense gives you," Kill said.

Big Ten defenses will devise schemes to stop the Gophers running game and force Leidner — or Streveler — to beat them. That happened last season and the Gophers finished 115th nationally in passing.

The assumption throughout preseason camp was that Leidner's development as a passer would make the offense more balanced. That hasn't materialized yet, even as the Gophers look better at their skill positions.

Leidner completed only nine of 17 passes for 144 yards in the season opener. He displayed a lack of touch on his passes again Saturday, overthrowing his receivers on several occasions.

He injured his left knee on a pass attempt in the fourth quarter that highlighted his struggles. On third-and-6, he sailed a throw high and wide of KJ Maye.

A Middle Tennessee lineman crashed into Leidner's knee as he released the ball, causing Leidner to limp off the field. Streveler entered the game the next series.

The coaching staff has been content to rely on the running game, even in passing situations. Rather than attempt a pass on third-and-17 in the third quarter, offensive coordinator Matt Limegrover called a run for Berkley Edwards.

What's the harm in trying a pass in that spot? Yes, they were trying to milk the clock, but the Gophers need as much work in the passing game as possible before Big Ten play.

Leidner's best moment came after the Gophers defense forced a turnover in the second quarter. On the first play, he found stud tight end Maxx Williams for a 27-yard touchdown, an easy throw and catch.

But that was the extent of Williams' production, a strange development since he's the Gophers' best player on offense. Williams was targeted three times in the opener, once Saturday. That makes no sense. If anything, Williams should be exhausted from overuse.

Those expecting to see the passing game start to click had to settle for the realization that improvement isn't a flip of the switch. And now Leidner's health is a concern.

The Gophers are 2-0, but their passing game has created an uneasiness that can't be pinned solely on first-game nerves.

Chip Scoggins • chip.scoggins@startribune.com