Nothing we've seen so far from Brau has shown him to be more than an interesting punt in the foreign market. He definitely hasn't yet looked like a reliable defender, and the complete misjudgement against Charlton reinforces that.
Equally, he's shown a few hints of potential with the ball, and as has already been said it can sometimes take players quite a while to adjust to the unforgiving environment of this league. I really don't understand the relish some people have for caustic criticism of our players.