If you're not aware by now, Pro Football Focus is a website that focuses on grading NFL players for their individual performances based on an in-depth review of every snap for every game. If you're interested, here is a look at their grading system.

Here is a closer look at the individual performances from Sunday's victory over the San Francisco 49ers.

Offense

Best Grades

Theo Riddick: +4.1

Matthew Stafford: +1.9

Eric Ebron: +1.3

Golden Tate: +1.0

Worst Grades

Travis Swanson: -3.7

Larry Warford: -3.1

Bear Pascoe: -2.1

Laken Tomlinson: -1.3

Michael Burton: -1.3

Analysis

Here's a nice statistic that'll catch you off guard: Theo Riddick has the third-highest PFF grade (+14.0) among all running backs. Only Doug Martin (+17.1) and Le'Veon Bell (+14.4) have higher grades. Riddick leads all RBs in YPRR (yards per route run) with 2.35 and would be seventh among all receivers.

Pray for this unnamed soul, whose ankles fell victim to Sir Theo Riddick: First of his Name, and Leader of the Backfield.

Eric Ebron also had a pretty nice showing. Give credit where it's due, offensive coordinator Jim Bob Cooter is learning how to put him in position to succeed. The key has been to give it to Ebron in space and let him show off his speed. Hopefully, for Detroit Lions fans, we'll see a lot more of that next year.

While most of the skill players had a great day, that was not the case for the interior line. Warford, Swanson and Tomlinson all had negative grades, with Swanson earning the worst. Swanson had a rough day both pass blocking and run blocking, while also getting flagged for a penalty. Warford's low grade was exclusively due to his poor run blocking (-4.1).

Matthew Stafford continues to build off of his strong start to the second half and here's some news that will make everyone happy.

Don't look now, but Matthew Stafford has a better QB rating than Aaron Rodgers. — Kyle Meinke (@kmeinke) December 28, 2015

Defense

Best Grades

Haloti Ngata: +3.8

Josh Bynes: +2.3

Ezekiel Ansah: +2.2

Tahir Whitehead: +2.1

Quandre Diggs: +1.2

Worst Grades

Kyle Van Noy: -2.5

Stephen Tulloch: -1.8

Caraun Reid: -1.7

Isa Abdul-Quddus: -1.2

Glover Quin: -1.1

Khyri Thornton: -1.0

Analysis

That marks six of Diggs' last seven games in the 'Best Grades' category. I think I've said almost all I can say about Diggs lately. He's been flat out awesome. Whether it's in coverage or against the run, he is your quintessential nickel corner that plays tight coverage and loves to tackle.

It only took him about 12 weeks or so, but Haloti Ngata is finally living up to his reputation of being a force in the trenches. He's earned himself a +8.6 overall grade over the past six games.

I know you're all missing DeAndre Levy this year, but let's give Josh Bynes some credit for arguably being the Lions' best linebacker this season. You could also make a case for Tahir Whitehead, who despite being benched for some of the year, has proven to be a reliable coverage linebacker for the Lions.

Kyle Van Noy earned a -2.5 overall grade on just 10 snaps. I'm afraid KVN just isn't what we thought he'd be, at least not right now with this current coaching staff.

Special Teams

Best Grades

Sam Martin: +3.4

Matt Prater: +1.9

Worst Grades

Travis Lewis: -2.0

Analysis

Travis Lewis missed a tackle and was flagged for a penalty on special teams, while Martin and Prater were their usual efficient selves.