Booger McFarland compares Rams DT Aaron Donald to Hall of Famer Warren Sapp because of how similar their explosive styles are in playing football. (1:01)

THOUSAND OAKS, Calif. -- The secret to Aaron Donald's astounding success lies in a conventional spiral-bound notebook. That's the word, at least.

"Oh," Donald says, his eyes lighting up, "you want to see it?"

The Los Angeles Rams' standout defensive tackle reaches into his locker, takes out his black leather backpack, pulls on the zipper, and there it is, with a plastic, dark-blue cover, a ball-point pen wedged in the middle and his name autographed in purple marker on the front, just in case there is any confusion. He flips to the first page, and the word "49ers" is written boldly up top, right at the center, underlined three times to indicate the Rams' first opponent this season.

The rest is unrecognizable.

There are notes scribbled on the left, a few more scattered to the right, a phrase here, a word there, some indiscriminate doodles throughout. If anybody else saw this ...

"They'd be like, 'What the hell is this?!'" Donald said, laughing. "There ain't no order. I might put something here, put something there. It’s all over the place. I can read it, so that’s all that matters."

In it, Donald notes every advantage he can possibly glean from wathing film. He began doing it his junior year at Pittsburgh, realized how much faster it made him play and quickly became obsessed. When he first arrived in the NFL, as the 13th overall pick in 2014, veteran players on the Rams were already mimicking his study habits. And now, as a third-year pro who is undoubtedly the game's best interior lineman, Donald has become almost neurotic about analyzing film and jotting down every detail in the hopes that it will make him just a little bit better.

"I’m one of those guys who takes great notes and tries to share them," Rams defensive tackle Michael Brockers said. "But you look at his notes, and it’s like you’re looking at a science project or an equation or something like that. It’s just terrible. But in his world, he knows what it is."

It's how the guard moves his feet.

It's how the tackle shifts his eyes.

It's where the placement of his hands are when he comes out of his stance.

"Every little thing," Brockers said. "And it helps him."

Donald picked up a couple of sacks Sunday in a 13-10 loss against Carolina. It brought his season total to five, tied for eighth among defensive linemen and second only to the Jets' Leonard Williams among defensive tackles.

That doesn't even begin to tell it.

Donald has already compiled 49 total pressures on opposing quarterbacks, tops in the NFL and an incomprehensible number for an interior rusher who barely sees snaps on the edge. Pro Football Focus gives Donald a grade of 95.6 thus far, making him the second-highest-graded player in the NFL behind Tom Brady, who has played in only half the games. The subscription-based analytics service rated Donald the game's greatest player last season, regardless of position, and this season Donald believes he has improved.

"The production might not show, but I feel it," Donald said. "I just feel a lot more comfortable, that there’s different things that I can do as far as pass-rushing and changing up things that are helping me a lot more this year."

It comes primarily from his physical ability -- from his low center of gravity, from his lightning-fast hands, from his powerful build, from his sheer explosiveness.

"God built him to play D-tackle, man," Brockers said. "He built a 6-1, 280-, 290-pound bowling ball with the strength of two men."

But teammates will tell you Donald has taken his game to another level with his study habits, a lot of which have been honed by additional NFL experience.

"I felt like past years he was playing more solely off pure talent and how explosive he is," Rams middle linebacker Alec Ogletree said. "But this year you can definitely see the growth in how he understands how teams want to block him and do stuff to him to try to slow him down."

Donald can only survive if he studies. He faces so many double- and triple-teams that the only way he can truly make an impact, the only way he can consistently get to the quarterback, is if he can anticipate plays and blocking schemes and even idiosyncrasies. It's why he spends so much time jotting down notes and circling back to them.

"I’ve learned to understand things a lot more," Donald said. "I always take it like studying for a test."

Donald -- also with an NFL-leading 12 tackles for loss -- is now widely considered the game's best defensive player, even while playing a position that isn't one of the sexiest. With Texans star J.J. Watt on injured reserve, Donald has a legitimate chance to be named the NFL's Defensive Player of the Year in 2016. That is, if voters can look past the raw sack totals and realize just how often he bursts through offensive linemen.

"It would be awesome," Donald said. "But I’m just doing my job. If it happens, it happens. But my main focus ain’t that. When you start focusing on things like that, you start putting pressure on yourself. Just play the game. At the end of the year, whatever happens, happens."