Ranking every unit in the College Football Playoff semifinals, 1-16

The national college football semifinal matchups will bring together four teams from different conferences – none of whom have played each other this season.

So how can we stack them up against each other? We ranked each of the four teams’ passing offenses, rushing offenses, pass defenses and rush defenses – 1-16 – based on those units’ performances this season in PFF grades. Here’s how each unit ranked:

1. Alabama run defense

There might not be a team in the country that can run on Alabama, and Michigan State isn’t likely to be the one to find success. Jarran Reed and A’Shawn Robinson both rank way up in PFF’s run-defense grades (No. 2 and No. 16 among interior defenders, respectively), and the additional presence of Jonathan Allen up front and linebacker Reggie Ragland makes this the best front seven in the country.

2. Oklahoma passing offense

Baker Mayfield ranks No. 1 in our PFF quarterback grades, and boasts an outstanding 48 percent completion rate and 10-to-0 TD-to-INT ratio on passes 20 or more yards downfield. Sterling Shepard is our No. 1 wide receiver, as the game’s most dangerous slot weapon who can beat defenses underneath or over the top. The one weakness on this unit is in pass protection, but it hasn’t mattered. That’s because Mayfield’s QB rating when facing pressure this season is better than any other quarterback earned overall – which is a truly remarkable stat.

3. Alabama pass defense

To be fair, the Crimson Tide really haven’t faced an elite passing game yet this season. Michigan State will pose their biggest challenge through the air on the season. But it’s also true that Bama has absolutely shut down opposing passing attacks. The Crimson Tide’s pass coverage ranks No. 1 in the country, while their pass rush has improved over the course of the season and now ranks No. 3 in our grades, led by the emergence of linebackers Tim Williams and Ryan Anderson.

4. Michigan State passing offense

The biggest key to victory in the Alabama game for the Spartans will be whether they can provide quarterback Connor Cook with time to throw. He is the best passer the Tide defense has faced this season, by quite a large margin. Cook ranks No. 6 in PFF quarterback grades in Power-5 play, while posting a very impressive 21-to-4 TD-to-INT ratio on throws 10 or more yards downfield. But his passer rating drops by 53 points when the opponents’ pass rush gets to him – essentially transforming him from a top-5 quarterback to an average one. Michigan State’s offensive line has been very good the last few weeks after dealing with injuries early in the year, and left tackle Jack Conklin in particular was a standout in the Big Ten title game win over Iowa. But the Tide’s pass rush figures to pose a much bigger challenge than the Hawkeyes’ did. If Cook does have time to throw, he’s got a big-play threat in Aaron Burbridge, who ranked first nationally with a deep-ball catch rate of 64 percent.

5. Alabama rushing offense

This year’s Crimson Tide offensive line isn’t nearly as dominant as the ones we’ve grown accustomed to in recent years. But they are better run blockers than they are pass protectors (with the exception of left tackle Cam Robinson), and they’ve got Heisman winner Derrick Henry in the backfield. Granted, we wouldn’t have given Henry the award based on how we graded him relative to other backs like Stanford’s Christian McCaffrey, but he did have a fantastic end to his season, leading the nation in broken tackles versus Power-5 competition (61) and ranking third in our rushing grades.

6. Clemson run defense

The best unit on the Tigers this season was their run defense, ranking 11^th in PFF grades in that area. Defensive ends Shaq Lawson and Kevin Dodd were major contributors in that regard, as were linebacker B.J. Goodson and safety Jayron Kearse at the second and third levels, respectively. Overall, Clemson had zero regular contributors earn poor run-defense grades – the key to beating this team will likely be through the air.

7. Oklahoma pass defense

The Sooners’ pass rush got stronger as the season went along, particularly in the form of undersized edge rusher Eric Striker, who finished sixth among edge defenders in Power-5 play in PFF’s pass-rushing grades. Charles Walker and Charles Tapper also do a good job of generating pressure up front. On the back end, the Sooners were solid at the cornerback spots and even better in underneath coverage, excelling against the shorter pass patterns that Clemson leans on the most – outs, screens – while also shutting down opponents on go routes, the Tigers’ other weapon of choice. This isn’t necessarily a shutdown pass defense, but a good one overall.

8. Oklahoma run defense

The Sooners were very effective at defending the run this season, led by a very talented defensive front. Charles Walker ranks 10^th in PFF’s run-defense grades among interior defenders, and Matt Dimon, Matthew Romar and Charles Tapper add to their strength up front. The Sooners don’t have any major liabilities at the second or third levels, either.

9. Clemson pass defense

The Tigers’ pass rush was good but not great this year, ranking 46^th in the country. Lawson was very effective when averaged out to a full season, but was up and down in individual games, earning negative pass-rushing grades in four different contests while posting very good grades in games versus Louisville, Miami and UNC. When he’s at his best, this is a very good pass rush. The pass coverage is arguably even better, with Kearse offering solid contributions from his safety spot and their pair of talented starting cornerbacks Mackenzie Alexander and Cordrea Tankersley also earning positive grades. They haven’t faced a passing game like Oklahoma’s yet this season, however.

10. Michigan State run defense

The Spartans were solid in run defense this season, just not exceptional, which could give MSU fans some cause for concern ahead of the matchup with Henry and the Bama running game. But Lawrence Thomas and Malik McDowell both graded well up front, as did Jon Reschke from the linebacker position. The bigger issue is that star edge rusher Shilique Calhoun barely registered a positive grade against the run, instead achieving the vast majority of his success rushing the passer, and linebacker Riley Bullough was something of a liability in the run game.

11. Oklahoma rushing offense

The Sooners’ offensive line earned a top-20 run-blocking grade this year, proving particularly adept at opening up holes on the left side of the line. They created room for running backs Samaje Perine and Joe Mixon, who overcame slow starts to rank 14^th and 16^th, respectively, in PFF’s RB grades versus Power-5 competition. Their combined 77 broken tackles on the season is a very impressive number, as is their 6-plus yards per carry average.

12. Clemson passing offense

The Tigers’ passing game is a little tough to figure out. The offensive line allowed their QBs to be pressured on just 22 percent of dropbacks this season, nearly 10 points below the NCAA average, but they didn’t grade particularly well in pass protection. Watson was a Heisman candidate and ranked No. 2 versus Power-5 teams in accuracy percentage, and No. 4 in our overall quarterback grades, but a lot of that was based on his success as a runner. And while he fared pretty well when throwing deep, he also threw a LOT of short stuff this season, with 38 percent of his passes coming on WR screens and out routes, well above the NCAA average. It’ll be interesting to see how well he fares if the Oklahoma pass rush gets to him without having to bring extra rushers (Watson was only OK versus pressure, while faring much better when blitzed), and if they take the shorter throws away from him.

13. Michigan State rushing offense

This was a very good run-blocking Spartans line when everyone was healthy this season, particularly on the left side with center Jack Allen, guard Brian Allen and tackle Jack Conklin. In the last three games in particular – wins over Ohio State, Penn State and Iowa – that trio was outstanding in the running game. The Spartans didn’t feature a single star at running back this season, but Gerald Holmes, Madre London and L.J. Scott all graded positively. They’ll have their work cut out for them versus Alabama’s defensive front, but this isn’t a complete mismatch, either.

14. Michigan State pass defense

The Spartans’ pass rush is excellent, with Shilique Calhoun a terror coming off the edge (No. 2 pass-rush grade among edge defenders) and Malik McDowell creating pressure up the middle (No. 12 pass-rush grade among interior defenders). The pass coverage is an issue, however, with cornerback Arjen Colquhoun (who really came on from Week 7 forward) the only major contributor in the secondary to earn a positive coverage grade. They do have a pair of good coverage linebackers in Riley Bullough and Darien Harris, however.

15. Clemson rushing offense

This is another tricky one to figure out, because while Watson and running back Wayne Gallman both fared well in our rushing grades, the run blocking of the Clemson offensive line might be the biggest positional weakness in the entire Final Four. The Tigers had just one major contributor on the offensive line earn a positive run-blocking grade this season, and it could be tough to run the ball on a good Sooners defensive front, leaving them to rely on Watson’s scrambling ability more than usual.

16. Alabama passing offense

There are reasons why this unit ranks at the bottom of the list. This is not a good pass-protecting line. They don’t have a true No. 1 receiver like they did last year in Amari Cooper. Jake Coker ranks just 73^rd in our QB grades, by far the lowest of the four national semifinalists. But there are also some reasons for optimism. Kenyan Drake has proven to be a very effective weapon as a receiver out of the backfield, wide receivers Calvin Ridley and ArDarius Stewart have made some big plays down the field in recent weeks, and Coker has gotten better as the season has gone on. When given a clean pocket from which to throw, he’s an above-average passer. Bama just needs to make sure it can keep MSU star pass-rusher Calhoun away from him.