I just believe not every player playing where he does can be first class at every aspect of the game required of him for that particular position. Such players are very few. Granted Mascherano doesn't have the best passing range and vision, he does a great job of breaking up play which is the most important part of playing where he does.
I really like Frimpong for the same reason too, very decent on the ball but looks to have great ball winning ability for his age. Gilberto wasn't the best passer either, nor the greatest ball-winner but his positioning was impeccable and he played alongside a great ball winner. I would rather someone be brilliant at one facet than be average in everything.
This is where i believe Wenger has failed with his defensive acquisitions at times over the past few years. He has ostensibly been looking for good defenders who are also very good on the ball to facilitate the game we are trying to play.
Anyways, i don't know why i had to say all that, we aren't signing Mascherano.
