Frederick is one of the safest picks in the entire draft. You get what you see, which is a very strong, aggressive, mean, huge center who is strong, smart and can play guard. Not much room for downside there. He has played in a pro style blocking scheme in college, excelled at it, and will be doing the same exact thing in the pros. While the C position isn't sexy, it is a neccessity.
Not at Center. He was the highest rated pivot guy on the Cowboys board and they deemed it very important to get that fixed this offseason. They absolutely loved his physical skills, his smarts and as this article points out, his mean, aggressive attitude. No longet is the center of the Cowboys offensive line soft... either physically or attitude wise.
Considering what the Cowboys needs were and how important getting a huge, smart, tough guy to anchor their OL, I'm not so sure there were a lot of better picks, frankly.