Neto is a big powerful man - 6'4" 330lbs - (a lot of muscle). But as gregorygrant83 highlights above, he's now 28. Back in Brazil he was a top judo fighter and won awards. I'm sure one on one, he is physically powerful.
To be real, the chances of him making it in the NFL are probably extremely low. However, because of his international heritage (and the NFL's desire to develop a global following and generate additional revenue streams eg foreign TV), he doesn't count on the practice squad #s. As such, he is effectively an additional big strong body to be used at training - to physically challenge our D-linemen. If he was really bad and not contributing, the Dolphins would have moved on from him and not wasted further time, money and effort in his development. It's a pity we had no preseason games, I would have been curious to see the big boy in a game. BTW - He has a degree in agricultural engineering.