I think a lot of it is people seeing the opportunity cost, mainly Odell Beckham.
However, something that clearly stands out is Beckham's targets (132 in 12 games, 116 in his last 9 games) vs Sammy's targets (128 in 16 games, 67 in his last 9 games). Simply put the Giants were forcing the ball to Beckham while losing games (4-8 in games beckham played, 1 win was his first game where he only had 5 targets). We had our offensive struggles and perhaps did not utilize Sammy to his full ability yet finished with our first winning record in years.
Beckham is similar to the Brady draft rule. No one believed he would be this good, otherwise he would have challenged for the #1 pick. It takes a tremendous amount of hindsight to say "we really screwed the pooch there, could have had Beckham and our pick". No one is operating in hindsight in the draft and Sammy looks like a real player as well. If anything we should be more inclined to believe in Whaley as Beckham and Zach Martin were the other guys besides Ebron we were targeting at 9, both of those guys were panned as reaches there and they look like two of the best rookies so far.