I have to agree with the assessment of his strengths and weaknesses but not the "freak athlete" moniker. 9.9 on the RAS is pretty impressive but in reality that measurement does not change the fact is is a backup at best.
When I watched Farniok play I saw two things. He is a very good run blocker and shows the meanness you want to see. He does not stop after blocking one guy. He often looked for a second guy to take on if he can. His run blocking abilities are more than adequate to play backup or even start at C or G.
His weakness is definitely pass blocking. He is slow to get up and get his hands on quicker DTs. Too often they get their hands on him first and when that happens the battle is over. Farniok will get showed around if he does not get his hands up and on the defender, He improved this as a C but I still see him get caught by the shoulder pads as a LG. This is his 3rd year. I don't know if this is something he can improve at this point which limits his development.
Still, nothing I saw from him in preseason says he is not better than Brock Hoffman, who is pretty awful himself.
I suspect Farniok said something to the Dallas coaches when he was informed he would be cut and re-signed to the practice squad. Something along the lines of "***** this, and ***** you!". He signed with Chicago's practice squad, but players often go there before getting promoted to the active roster, especially if the signing team needs to clear a roster spot first. We'll see what happens to Farniok going forward. I wish him good luck as I would any former Cowboys player.