I notice a few things about him that stand-out:
1) He's very quick off the snap, great use of hands to fight off the block, slippery and agile through the gaps, and has the athleticism to mirror QB and RBs in a chase.
2) He's a violent tackler, in which I saw two trademarks, when he's in front of the ball carrier, he uses his leverage to get lower and then explodes into the b/c taking them off their feet, and when he's to the side or behind the ball-carrier, he uses his long arms to grapple around the body of the ball-carrier into a bear hug and then tosses the b/c to the ground like a rag doll. Also, a lot of bowling ball moves where he grabs the legs/hips, rolls into the ground catapulting the ball carrier into the ground as well.
3) The biggest games seemed to bring out the best in him, the bigger the opponent, the more energy he seemed to generate.