I know there has been more than enough discussion on the trade, and this was mentioned already, but I thought this might be worthy of its own discussion (especially since the latest thread has gotten so cumbersome). If not, feel free to delete it.
I think the key to the Giants thinking on this trade is found in this short quote from a Ken Rosenthal article:
One general manager, though, isn't impressed with Alderson, calling him "overrated" and saying, "They had a long list of untouchables, and he wasn't on it."
If it's true that they had a long list of untouchables that indicates to me that the Giants weren't desperate to make a trade to satisfy the fanbase and didn't have delusions of grandeur about the current team. It seems that maybe they had a prudent approach to the trade deadline and just simply were not that high on Alderson. Are they correct in their assessment of Alderson? I guess time will tell.