The second time has been the charm for Notre Dame and a transfer quarterback out of the ACC.

Last season, the Fighting Irish and coach Marcus Freeman brought in Wake Forest transfer Sam Hartman, one of the most productive passers in ACC conference history. Results were mixed: Hartman threw for 2,689 yards and 24 touchdowns but the Irish lost three times and never factored into the College Football Playoff mix.

Notre Dame went back to the ACC for Duke transfer Riley Leonard, who after a slow start — for the senior and the Irish — has become the face of this year’s march to the national semifinals. Leonard and the Irish meet Penn State in the Orange Bowl on Thursday night.

"I think what he was able to learn is that you can’t get your joy from what outsiders are saying about you. You get your joy from playing this game with your teammates,” Freeman said. “You play this game with confidence. And that’s where I’ve seen him grow the most is the confidence that he’s playing with.”

In the four months since a stunning loss to Northern Illinois, the Irish have evolved into a defense-focused intimidator capable of hammering Georgia in the Sugar Bowl.

Mirroring that growth has been the development of an offense that has embraced a more predictable, meat-and-potatoes style. Driven by Leonard, this throwback approach has Notre Dame nearing the finish line of the program’s first national championship since 1988.

He won at Duke, too, going 14-7 as the starter across his final two seasons and leading last year’s team as high as No. 16 in the US LBM Coaches Poll to match the Blue Devils’ highest ranking since the 1994 season.

After getting through some early growing pains, the marriage of Leonard and Notre Dame has become one of the biggest success stories of last year’s transfer cycle. Only one game during the current 12-game winning streak has been decided by a single possession while Leonard has accounted for at least 200 yards of total offense in all but two games.

“Man, he is so competitive,” said Freeman. “He finds a way to get his job done. And we’re so grateful to have him here.”

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Far from explosive in the passing game — the Irish are one of nine Bowl Subdivision teams with fewer than two completions of 50 or more yards — Notre Dame has become a wrecking ball by leaning on the three-headed running game of Leonard and running backs Jeremiyah Love and Jadarian Prince.

Combined, these three have run for 2,627 yards, more than all but 17 other teams in the Bowl Subdivision, with 38 touchdowns. Leonard has accounted for 831 yards and 15 touchdowns on 5.6 yards per carry.

The senior has taken on an even bigger role in the playoff. Leonard has 25 carries in two playoff games, including a season-high 14 carries in the win against the Bulldogs. The Sugar Bowl also showed how Leonard has become the fixer for Notre Dame’s offense, delivering crucial conversions and helping the Irish pull away in the second half.

On the year, Leonard is averaging 6.2 yards per carry in the second half and 6.1 yards per carry when Notre Dame leads by more than a touchdown. He had two third-down conversions on a more than seven-minute drive in the fourth quarter that helped close out the win against Georgia.

“It was going to be a physical matchup,” Leonard said. “Our number one key to victory was the line of scrimmage on both sides of the ball, and that's exactly what we did. We knew if we could establish ourselves up front, we were going to have a chance at this thing.”

The offense has ranked among the most prolific in program history despite the lack of anything resembling an explosive passing game: Notre Dame is fourth nationally at 37.7 points per game. But this approach makes the Irish stand out among the remaining playoff field.

The closest analog would be Penn State, painting the Orange Bowl as a low-scoring matchup decided by turnovers and defense. But the Nittany Lions are dynamic in comparison with the Irish, averaging nearly an additional two yards per pass attempt with one of the top quarterback-efficiency ratings in the FBS.

Being a little different has worked out for Notre Dame. The Irish are averaging 30.3 points per game when attempting 30 or more passes, an average inflated by a 52-point outburst against Florida State, and 39.9 points per game when making fewer than 30 attempts.

The formula has still delivered one of the hottest stretches in recent program history. Since the loss to Northern Illinois, the Irish have averaged 6.7 yards per play and 40.9 points per game. Leonard accounted for at least one score in every game during this span and had just four interceptions in 287 attempts, or one for roughly every 72 throws.

Once again, Leonard and his ability to protect the football while playing a leading role in the running game will hold the key in the matchup with Penn State.

“As you look at the course of our season, it's been a big indication of the outcome of the game, our ability to run the football and our ability to stop the run,” Freeman said. “It's a mentality. It's a mindset.”

This article originally appeared on USA TODAY: Notre Dame needs Riley Leonard for College Football Playoff success