I believe Chris Johnson has everyone believing that the NFL trend is to get faster and lighter at Safety. Johnson creates huge match up problems. The old in the box safety of the eighties and nineties is becoming at the very least, out of vogue.The old theory was to mash the line with a big safety, eight and nine in the box, on first and second down. Make the other team throw the ball on third and long. You know what they are going to do there fore you have a chance to defend it. Send in the nickle or dime according to down and distance.
Now, JMHO, it's to counter being stretched by the offense side line to side line and vertical to set up bad match ups with slow LBS and the old in the box will backer sized safety by the offense. Earl Thomas is the face of the future and coveted by the NFL. Fast instinctive and can cover anyone, including Johnson in the slot. Same is not true with slow hipped Taylor Mays. He is not instinctive. He can not cover anyone in the slot. On third and long he will be the match up target the OC's are going for. Taylor Mays was a bullet dodged. I also believe if this is true, the Texans theory of inter changeable safeties is now DOA. The sooner the Texans adapt, the better. Aggies hate change. We'll see.