By JOHN SHIRLEY

It has been an unprecedented college football season, as teams and conferences have dealt with the coronavirus pandemic. But even in a year like no other, the teams at the top have remained mostly the same as the season turns to Friday's national semifinals.

Clemson and Ohio State will face off in a rematch of last year’s Fiesta Bowl semifinal, while Alabama and Notre Dame return to the College Football Playoff for the sixth and second time, respectively.

Using Sports Info Solutions’ advanced metrics and charting data, let’s take a brief look at each team’s success this season.

No. 1 Alabama

Even after losing its starting quarterback and two first-round wide receivers from last year’s team, the Alabama offense hasn’t missed a beat this season. It is led by Heisman Trophy finalists Mac Jones and DeVonta Smith. Jones has been incredibly accurate this season, as he currently only sits 0.2 percentage points off of the single season completion percentage record of 76.7%. His 83% on-target percentage (how often a quarterback throws a pass that hits his receiver in stride) ranks second in the nation, and he ranks first with an Independent Quarterback Rating (IQR)* of 143.5.

As impressive as Jones’ season has been, there is good reason that Smith is the favorite to take home the Heisman. He currently leads the country in receptions (98), receiving yards (1,511), ranks second with 17 receiving touchdowns, and has dropped only two passes. Also, his receiver rating of 153 (the passer rating on throws where he is the intended target) is the highest of any player since SIS started charting college football data in 2016.

* Independent Quarterback Rating is Sports Info Solutions’ proprietary quarterback metric. It builds on the traditional Passer Rating formula by accounting for results that are outside of the quarterback's control – dropped passes, dropped interceptions, throwaways, etc. – to form a better benchmark of QB value.

No. 2 Clemson

Clemson is once again led by quarterback Trevor Lawrence and running back Travis Etienne. Lawrence is also a Heisman finalist, even after missing two games this season. He currently leads the nation with an on-target percentage of 84%, ranks 9th in passing yards per attempt at 9.6, and also 9th with an IQR of 127.7.

Etienne has had a productive year, despite not reaching the same level of success as the last two seasons. He has declined in yards per attempt, yards after contact per attempt, and broken tackles per 100 carries. That said, he still ranks 30th nationally in yards per attempt (5.6), 14th in yards after contact per attempt (3.4), and 19th with 24 broken tackles per 100 carries.

No. 3 Ohio State

The rematch of Clemson and Ohio State will also feature a rematch between top quarterbacks Lawrence and Justin Fields. In a shortened season, Fields has had similar success to his first season as a starter. His on-target percentage has increased by about two percentage points to 75.5% and his yards per attempt has held steady, going from 9.2 to 9.3. However, his IQR has dropped 14 points to 118.3 due to an increase in interceptable passes. Last season he had 10 interceptable passes (three intercepted passes, seven dropped interceptions) on 354 attempts. This season, he had seven on 164 attempts.

On defense, Ohio State is led by first team AP All-American corner Shaun Wade and second team AP All-American defensive tackle Haskell Garrett. Wade has allowed only 18 completions on 34 targets against him, has intercepted two passes, and dropped two other potential interceptions. Garrett has forced 14 quarterback pressures and recorded two sacks from his interior defensive line position.

No. 4 Notre Dame

Notre Dame enters the playoff coming off a disappointing loss to Clemson in the ACC championship game but has had an impressive season nonetheless. As with the other three semifinalists, Notre Dame is led by strong quarterback play from Ian Book.

Book has had an efficient season throwing for 2,605 yards and 15 touchdowns to only two interceptions. His on-target percentage of 78% ranks in the top 15 nationally, his IQR of 113.6 ranks 21st, and his interception percentage of 0.6% ranks second among quarterbacks with at least 150 attempts. On the ground, Book has added eight touchdowns and 29 first downs.

On defense, Notre Dame is led by AP All-American linebacker Jeremiah Owusu-Koramoah. He has been stout against the run and the pass. He ranks third on the team with 51 total tackles, has forced three fumbles, and has forced 12 quarterback pressures. He has also allowed only 12 completions on 25 targets for 4.7 yards per target against him.