I watched the all passes from the Giants a few times and I counted 3-3.5 passes that were low, and on the .5 it can be argued that where he placed it protected the receiver. Anyway, there were several passes that were forward or high to the receiver, why don't you think those are evidence of excessive arm strength?
Even guys with monster arms like Matt Stafford make the occasional shallow pass, it doesn't mean that he lacks arm strength, it just means that is was a bad pass, it happens.
Anyway, it seems to me that you're trying to downplay Grop's skills in order to justify your desire to trade him for Zach Martin, which I think are two completely separate issues. I think Grop is a very intriguing raw talent and I'm very fond of him but I'd still trade him for Zach Martin in a heartbeat for one simple reason: a Lombardi in the hand is worth a dozen in potential.
Kraft likely doesn't share my opinion, he wants always wants a QB who is sufficient to keep the team competitive so the team can continue to charge a lot and still sell out, as a fan I don't care about that, I want Lombardis, which is why I want Martin.