I'm sorry that I can't really answer your question. Grayshirts are relatively new, and while growing, still aren't all that common. From memory, I can't recall Ohio ever actually using one before. They tried, last year, with Pierce Royster, but he ended up at Wyoming instead. That, apparently, is fairly common: when a school offers a grayshirt instead of an immediate scholarship the kids often will not accept it, and go elsewhere.
I did a quick search, and found this story:
http://tinyurl.com/ocq7oruIt describes some Michigan State experiences with grayshirts. One is a 2015 recruit, Chewins, who had previously committed to Miami, but who flipped to Michigan State as a grayshirt. He is "only" 6-7 237, and the extra year will give him more time to bulk up to play Offensive Tackle. The other grayshirt mentioned in the article is Jack Conklin, who grayshirted, then redshirted his first year, and now is a projected high draft choice at Offensive Tackle.
Given that Ohio has never used grayshirts before, that I know of, having four in one class is really jumping in with both feet.