I wouldn't hang on to nicks, but at the same time his potential still looks to be higher than lacy. Cruz is getting what few good balls are being throne in NY, and the O-line hasn't shown anything to believe Eli will start throwing more good balls.
So Morris is a start, and i think geo bernard has a BIG upside, especially if Andy Dalton continues to throw short balls. He won't be Darren Sproles, but i see some Matt Forte in him. Think maybe 350 yards receiving on the year, with maybe 900 rushing yards as they use him more. So really i think you are OK on backs, but a real #2 or flex back would do you good. See if you can get a better trade or anything is on the free agent market. You won't be getting a #1, but i just picked up Ben Tate. I see him, benjarvus as a pair with geo, maybe Pierre Thomas, they all look to have a bigger upside than Lacy. As for WR, hang on to Mike Wallace. If you remember the second fin's game, he put up like 110 yards and 2 touchdowns, but he was being used all over the field instead of just deep bombs and a few screens. I think the Dolphins will try to use him like that again.
In the end Nicks might not be worth it for quite a while, but he still is worth more than a back who is shown to be injury prone and has other good supporting backs.