Excerpt below from MMQB on dearth of safeties, and the challenge of finding big safeties that can match up with large TEs. Isn't Reggie Nelson only 5' 11"?
"This is what makes Iloka’s soft market so puzzling. He had some cornerbacking experience at Boise State. More importantly, he’s 6' 4" and 225 pounds, with long arms. He might not be able to shut down Rob Gronkowski on an island for four quarters, but he has the physical tools to compete with an athletic pass-catcher of Gronk’s mold.
Of signed NFL safeties who play meaningful snaps on defense, only a dozen are at least 6' 2". Only eight weigh at least 225 pounds, and only seven others weigh more than 215. An average tight end runs somewhere around 6' 6", 245, and defenses simply don’t have big enough athletes in the deep middle of the field to compete with these versatile offensive weapons.
The problem will only get worse before it gets better. This year’s draft class is particularly weak at safety. Only four of most experts’ top 20 safety prospects are 6' 2". And none weigh more than 219."