(John McDonnell/The Washington Post)

Shawn Petty sat stone-faced inside Gossett Team House on Saturday, every bit as well mannered and easy-going as advertised in the days leading up to his debut start.

The absurdity surrounding these Terrapins engulfed the true freshman over the past two weeks, when Petty went from a scout team linebacker who was expected to redshirt to the quarterbacks meeting room, where his new teachers sported three pairs of crutches and one knee brace. Petty always believed he could become an FBS starting quarterback throughout his career at Eleanor Roosevelt High School, even as the only scholarship offers he received came from schools that wanted him to play defense.

“I was just ready to play. Next man up,” Petty said, repeating Maryland’s mantra for this season. “I just had to get prepared to play come today. Of course, I could always do better. I plan to get better. Our team is just going to move forward. I’m okay with it. I’m calm. Like I said before, I had time during the week, make sure I had my head right. Come Saturday, I was ready to play.”

On Saturday against Georgia Tech, Petty had an opportunity to prove the doubters wrong, to right the ship and rewrite the script of a season derailed by injuries to Maryland’s four scholarship quarterbacks. And Coach Randy Edsall never saw him get flustered, never saw those pupils dilate with fear, even after two turnovers, even after Maryland trudged off the Byrd Stadium turf with a 33-13 loss, its third straight.

Petty had spent the previous two weeks forgetting Maryland’s defensive schemes and learning offensive coordinator Mike Locksley’s attack, putting in extra hours in the film room and on the field and developing chemistry with his new receivers, with whom he had shared the field only on the opposite side of the ball during practice, mimicking the defensive looks of Wake Forest. Or Virginia. Or North Carolina State.

The Terps rallied around him once Caleb Rowe’s MRI exam revealed a torn ACL, tweeting out support and checking on him daily. Their hopes were pinned on Petty, as unfair and absurd as that may seem. But that spirit gave way to inexperience as Maryland fell behind 20-0 by halftime. The Terps mustered just 61 yards of offense in the first half, when Petty completed one pass that gained one yard. Maryland tried to take a shot downfield with the clock expiring from its 48-yard line, but Petty’s pass fluttered in the thick wind, abandoning its spiral and settling somewhere near the 20.

“You just don’t go out and line up at this level, only having seven practices, and think that everything’s going to happen the way you hope,” Edsall said. “Once he got settled in and we started to see what we could do with him, I think he showed his poise. The game still needed to slow down for him, but I thought he adjusted and moved the ball well in the second half.

“I think our guys have confidence in him. We need to make sure that we do the things that we need to do with him to get him more prepared. I thought he handled himself very well for the tough situation that he was thrust into today.”

Petty was markedly better after halftime, opening up running lanes alongside Brandon Ross, allowing the electric Stefon Diggs to make plays. He had done this before, running the read option at Eleanor Roosevelt, and the Terps adjusted accordingly during the break. Petty finished the game having completed 9 of 18 passes for 115 yards, his first career incompletion, completion, touchdown, interception, fumble and everything else imaginable knocked out along the way.

“I thought he held up well,” Ross said. “Shawn, normally, you’d see a freshman quarterback in his first start get nervous. I didn’t see him get nervous. At least, he didn’t show it. I think he played poised. In the first half, he was getting his feet wet, getting himself adjusted.”

Said Diggs: “Just becoming more of a quarterback. You could tell, in the first half, he was a little jumbled, got his mind rattled a little bit with a lot of pressure. He just became in his own, got a little more comfortable with his reads, like I said before. The second half, he became more of a quarterback, kept his eyes downfield, made his throws.”

The final throw, a 23-yard heave into the end zone that Diggs snatched out of midair, out-leaping the one-on-one coverage in the near corner, pushed Petty over the 100-yard mark and gave him two touchdowns, a high note and something to build on, especially with two ranked teams and 6-3 North Carolina looming to close the season. He also hit Diggs on a 16-yard slant route with 15 seconds left in the third quarter that cut Georgia Tech’s lead to 27-7.

“I told the team I am very proud of how he handled the situation,” Edsall said. “I think he earned a tremendous amount of respect from our team, which he already had, and from the opposing team. I have never had it happen before, and I hope this never happens again. I hope we can keep him healthy for the next three weeks.”

That’s the hope, but little has gone as planned for this Maryland football team after an unimaginable run of misfortune.