Two springs ago, I was watching Andrew Susac (Oregon State's current starting catcher, and whom PGjerry referred to that year as the best throwing high school catcher in the nation) throw out a runner in a high school game with a 1.79. The scouts there, four or five of them, had times on that throw that ranged from 1.76-1.81. One of the scouts commented "That's just wrong", to which I asked him "What is wrong, that he throws better than 1/2 of the catchers in MLB"? His comeback was that 75% of catchers in MLB probably couldn't make a throw with that time.
Nobody throws legitimate 1.6s. Nobody. A 1.8-anything is an outstanding in game time. Lots of in-game throws get runners with 2 flat or thereabouts, as there is a lot more to great throwing than just pop times.