Brewer has a physical maturity way beyond that of the normal college sophomore due to a four-year detour in minor league baseball. He also has a linebacker build (6-1 and 215 pounds). And, after starting the final six games as a freshman last fall, he's more comfortable with his assignments - making him even more dangerous.
"I'm not having to think as much," he said. "I'm more aware and able to react faster because I know my plays better."
Jackson, though packing just 187 pounds on a 6-0 frame, utilizes a rare blend of athleticism, aggressiveness and technique to leave opposing ball-carriers groggy.
So, while the 2011 Vols may be a little suspect in their front seven, their last line of defense projects to be downright imposing this fall.
"Obviously, when you've got guys roaming the middle of the field who can bring the wood like those guys can it gives us a tremendous advantage," secondary coach Terry Joseph said recently. "Hopefully, some receivers will hear some footsteps over the middle."
That's a safe bet. As the reputations of JJ and BB spread, some intimidated wideouts are sure to drop the ball before Jackson and Brewer have a chance to drop the hammer.
Proving that force equals mass times acceleration, the Vol duo can trace many of their forceful hits to the accelerated speeds they achieve in pursuit of opponents. In other words, Jackson and Brewer tend to be involved in high-speed collisions.
"The biggest advantage for those guys is that, not only can they hit, but they can move really fast," Joseph said. "So that really helps them be a lot more explosive."
Jackson earned second-team All-SEC recognition as a sophomore last fall but missed spring practice due to what head coach Derek Dooley called a "personal matter." Despite the layoff, Jackson hasn't missed a beat in the early fall workouts. That didn't surprise fellow Vol defensive back Prentiss Waggner.
"I think Janzen could take five years off and come back and be one of the greatest guys when you're testing 40s, verticals, bench press and all of that," Waggner said. "Janzen is just a guy that has raw natural ability."
Dooley took the five-years-off time line and expanded it even further, noting: "I would say longer than that he could."
Being in shape is one thing. Being in football shape is entirely different. From all accounts, though, Jackson has achieved the former and is closing in on the latter.
"Janzen's really getting back in football shape," Joseph said. "Brent had a good summer - worked his tail off - and he needs to get down about another five pounds and he'll be ready to go. Those guys are two exciting playmakers to have back there."
Unless you're opposing receivers running a route over the middle against Tennessee this season. Their prospects are (a) to be hammered by linebacker-sized Brent Brewer or (b) to be pulverized by super aggressive Janzen Jackson.
"I believe it puts fear in their hearts," Brewer said, flashing an evil grin. "That receiver running across the middle is a little scared to catch the ball when he knows you're going to hit him ... especially Janzen."
Although Brewer is older and bigger, he views Jackson as a big-brother figure.
"I like how he plays the game, so I look up to him," Brewer said. "Having him back is a big help. He covers so much ground. If you make a mistake, he'll cover it for you. I'm glad to have him back."
Pardon SEC receivers if they don't share Brewer's happiness.