The Patriots couldn't have fit the remainder or Sanders' 2019 contract under the cap at the trade deadline, so the comparison is a moot point. Sanu was a weird fit as a big slot on a team with a lot of slots (Edelman, Meyers, even Harry is probably best suited there), though in Atlanta he was always a very good red zone receiver, to the point where his touchdown totals regularly exceeded Julio's. But it's pretty clear he was a roll of the dice with the odds heavily weighted against him -- the positional fit, the lack of a true #1 as Edelman got beat up, learning a new offense midseason, a quarterback who seemed disinterested in integrating new players, then the injury,
It's hard to believe Sanu went from a very good complementary wide receiver in Atlanta to a trainwreck in New England literally over the course of a single week, so there are obviously other factors at play. Injury is one. Quarterback play is another. The other is learning the offense. If you watched Sanu closely, a lot of issues were with him being off on his releases, and ending up a half-second behind the play as a result. That stuff will get fixed in training camp and I expect him to be a contributor next season.
Harry's more of a mystery, if we should expect him to be Cordarelle Patterson or if we should expect more. The good news, I guess, is that Patterson is a useful player, but not exactly what you're looking for in round 1. DJ Chark and Mike Williams are both examples of receivers who were basically invisible their rookie season before emerging their second year, so it's possible.
I still think they need a top-flight guy though. Maybe Kraft forgives a cleared Antonio Brown, maybe Beckham. I don't know.