Most people have RJ near the bottom of the top 10, making him a 3rd or 4th round pick depending on how pitcher-happy your league is.
As far as taking him in the 2nd, I'd look at it this way. IF RJ does struggle this year due to knees/injury/whatever and you passed up say a Manny Ramirez or Curt Schilling for him, how pissed would you be?
I'd prob. make sure I had a few "sure things"(thought what really is?) on my roster before taking RJ. But the reward could be huge, since if healthy he is a top 5 pitcher.
As far as Kevin Brown, I'd say he's more of a risk. He already got injured this year,ha-ha, well not really took a grounder the hard way in ST. And he'll fall to you a bit later, most likely, maybe the 6th.
Hope that helps.