It's simply overstated.
ESPN Stats & Information tracks runs against a loaded box. That's any run front where the offense has fewer players available to block than the defense has in the front.
Any team or player claiming he faces loaded boxes "all the time" is exaggerating by a great deal, unless by "all the time" he means "less than a quarter of the time."
During Johnson's six seasons with Tennessee, among backs with at least 500 carries, veteran Thomas Jones faced the most staked boxes -- on 23.7 percent of his carries.
Let's dispense with the idea that CJ, or any back, is constantly running into loaded fronts.
Also, the whole benefit of drawing extra defenders into the box is that it helps open things up downfield.
Tennessee was hardly a big downfield passing offense during Johnson's time with the team.