CLEMSON — Clemson football is back as a national contender at the halfway point of its season.

The No. 9 Tigers (5-1, 4-0 ACC) entered the season facing questions about the lack of transfer portal players on their roster and quarterback Cade Klubnik and the offense. That continued after their 34-3 loss to No. 4 Georgia in Week 1.

Since then, Clemson coach Dabo Swinney's team rebounded to win five straight by an average of 29.4 points against unranked teams that have a combined record of 10-21.

Now, the Tigers sit atop the conference, winning as many ACC games this season as it won in 2023, are ranked in the top 10 in both polls and are on track to make the 12-team College Football Playoff.

"We got a chance to go into November where we hope to be, but it's all about how we play this week and just continuing to build," Swinney said after Clemson's win against Wake Forest.

Before Clemson hosts Virginia (4-2, 2-1) on Saturday (noon ET, ACC Network) at Memorial Stadium, here's why the Tigers have become national contenders again.

Clemson's Cade Klubnik has become an elite quarterback

The past five national championship winning quarterbacks ranked in the top seven in QBR, which values the quarterback on all play types on a 0-100 scale adjusted for the strength of opposing defenses faced.

Michigan's J.J. McCarthy (89.2 in 2023), Georgia's Stetson Bennett (86.3 in 2022; 86.7 in 2021), Alabama's Mac Jones (96.1 in 2020) and LSU's Joe Burrow (94.9 in 2019) all posted excellent QBR ratings to lead their respective teams to championships.

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Clemson quarterback Cade Klubik has an 88.4 QBR, which ranks fifth in the country. He has thrown for 1,528 yards for 17 touchdowns, two interceptions and rushed for four touchdowns too. He has lifted Clemson to No. 12 in scoring offense (41 points) and No. 10 total offense (482.3 yards).

The last three times the Tigers averaged 40-plus points, they reached the CFP. They averaged 44.3 points in 2018 to win the national championship, 43.9 to make the championship in 2019 and 43.5 to make the playoffs in 2020.

"When we go out there, we expect to make plays, and we go out there expecting to put 40 points on the board," wide receiver Adam Randall said.

Clemson's defense is elite despite inflated numbers

Clemson ranks No. 60 in total defense (348.3 yards allowed) and tied for No. 49 in scoring defense (21.7 points), but those numbers are skewed with the team removing its starting unit in the second half in four of its six games.

The Tigers are tied for 10th in defensive efficiency with 79.4 on a 0-100 scale, which is based on defense's contribution to scoring margin on a per-play basis and adjusted for strength of opposing offenses faced. The past four national champions ranked in the top 10 with Michigan having a 92.9 in 2023, Georgia with a 87.6 in 2022 and 93.7 in 2021 and Alabama posting a 77.6 in 2020.

Clemson's starting defense has been stout, generating the most turnovers in the ACC with 12 and holding opponents to 20 points or fewer in four games. Some standouts include cornerback Avieon Terrell, who has the second-most pass deflections in the conference with eight, and defensive lineman T.J. Parker, who has recorded six sacks, tied for the sixth most in the ACC.

Clemson football schedule for rest of 2024 is weak

They Tigers have a strength of schedule of 50 out of 132 after facing only one ranked opponent. Their remaining strength of schedule sits at 43 with only one ranked opponent on it — No. 20 Pittsburgh. As a result, they will likely be favorites in their remaining matchups of the regular season and clinch a spot to the ACC championship.

Thanks to the new CFP rules, a Power 4 team clinches an automatic bid to the playoffs and a first-round bye if it wins its conference.

Clemson's likely opponents will be No. 6 Miami, Pitt or No. 23 SMU — all undefeated in the conference but have flaws and a worse strength of schedule than the Tigers.

Derrian Carter covers Clemson athletics for The Greenville News and the USA TODAY Network. Email him at dcarter@gannett.com and follow him on X, formerly known as Twitter, @DerrianCarter00

This article originally appeared on Greenville News: Clemson football: Why Dabo Swinney, Tigers are playoff contenders