I've seen Blount make nice hands catches on his targets, so I don't know that his bad rap in that phase is warranted, but it really seems moot. The guy they replaced him with has ZERO targets through five games, so I doubt passing game utility actually played any role in the decision to sign Gillislee instead of re-signing Blount. Maybe they didn't like the fade you noted or maybe they just wanted to get younger. I don't fault them for it. "Should NE have stuck with Blount?" is not a question I've asked or tried to answer. I just took issue with the seemingly quick and universal assumption that Gillislee was some sort of automatic upgrade over Blount and due for a floor of 12 TDs (although if I'm being fair, he's still on pace for 12.8).
FWIW, it's been years since I've owned any Blount stock (and I play in a lot of leagues). I just feel obligated to stick up for him since I love watching him play.