Virginia quarterback Michael Rocco scores a touchdown, but later in the first half was hit hard and wound up being replaced by true freshman David Watford in the Cavaliers’ 30-24 loss to Southern Mississippi. (Steve Helber/Associated Press)

His defense is porous against the run one week and a sieve against the pass the next. His receivers drop passes at inopportune times. His special teams units are being uncharacteristically confounding. And he has but one nonconference game remaining before ACC play resumes.

 The last thing Virginia Coach Mike London needed — especially in the aftermath of a 30-24 loss Saturday to Southern Mississippi at Scott Stadium — was uncertainty at his team’s most important position. But that is the reality he faces.

Sophomore quarterback Michael Rocco entered Saturday’s game as the starter, but ineffectiveness against the Golden Eagles (3-1) and a vaguely described injury have clouded that status. After being hit hard while throwing his second interception of the day, Rocco was pulled from the game after throwing his third a short time later.

 In came freshman quarterback David Watford, and after a slow start, he led the Cavaliers (2-2) on a 10-play scoring drive that concluded with a dazzling two-point conversion pass. Over the course of five offensive series on the day, Watford completed 10 of 20 passes for 81 yards and a touchdown.

 Afterward, Watford said he felt he showed his coaches enough for them to feel confident in starting him next week against Idaho. But he also acknowledged that if Rocco is healthy, the team’s pecking order at quarterback will remain unchanged.

London said Rocco suffered an injury to his “midsection area” late in the first half and that Watford replaced Rocco late in the third quarter purely as a consequence of Rocco’s pain.

 Rocco said he felt “fine” entering the third quarter and that whatever pain he felt did not affect any of his second-half throws, particularly his third interception. He attributed his sub-par performance to “bad decisions.”

When asked how he felt after the game, Rocco replied, “I’m fine right now.”

Offensive coordinator Bill Lazor said he would not be able to decipher how much of Rocco’s struggles were because of injury as opposed to ineptness until he saw the game film.

“In the end, when you play quarterback, the final responsibility of the football is in your hands,” Lazor said. “Just like when you’re the guy calling the plays, the final responsibility is on you. You made the calls. So I’ll take it, and I’m sure Mike will, too.”

On the season, Rocco has completed 62.2 percent of his passes for one touchdown and seven interceptions. But Saturday night, London remained insistent that there was no quarterback controversy and gave Rocco a vote of confidence.

 “When I find out what’s wrong with him physically, then after that we’ll talk about if he can perform,” London said. “I’m worried about the young man’s health right now.

“If he can’t, then obviously that question is, ‘Who is going to be the quarterback for this upcoming game?’ ”

If Watford ends up being the answer, he provided evidence Saturday that, at the very least, he won’t be overwhelmed by the opportunity. Once he got into the flow of the game, he said, “it was like I was pulsing. It felt like nothing could stop me, for real.”

 London had said at the season’s outset Watford would be given a “limited menu” of plays to run in each game, and the Cavaliers stuck to that plan initially. In Watford’s first three offensive series of the second half, Virginia gained a combined 31 yards and two first downs.

But Watford completed 5 of 7 passes — including completions of 12, 13, 15 and 18 yards — on his fourth drive, which concluded with a one-yard touchdown pass to tight end Jeremiah Mathis. And when Watford scrambled to his right to evade a defender and then completed a two-point conversion toss to wideout Kris Burd, the crowd roared.

“To my understanding, [Rocco] is still number one and I’m still number two, so we’ll go from there,” Watford said.

“If they decide to start me next week or start him next week, we’re going to go out in practice just like we did last week, just execute and go with whatever the coaches tell us.”