I agree that no one is a steal yet cause it's too early. I would assume that people are talking more about guys who were picked late in the draft but have surprised and are having a great year.
My example would be Mathieu Aubin who was taken in the 5th round, 130th overall. This year he scored more goals then he had points in any other season. As one of the top scorers in the QMJHL this year, you could say his success was a surprise and that it's looking like a steal although the guy could end up never playing a game in the NHL. At this point and time though his offensive production could label him a possible steal.
Or a guy like Siarhei Kostitsyn who was picked in the 7th round, 200th overall but went on to lead the OHL in rookie scoring and has been among the top scorers in the OHL playoffs.
Chad Rau, Nikolai Lemtyugov, Anton Stralman, Matt Keetley, Tomas Pospisil, Slava Trukhno, Patrick McNeill, Keith Yandle, Cody Franson, Dan Ryder, Perttu Lindgren all come to mind as possible steals. In time we'll start to see which ones are steals. ( I left out all 1st and 2nd rounders since imo they aren't really steals that high)