Something to remember is that when a team acquires a player they also acquire the contract, and there are considerations for both teams associated.
Available salary cap is an equally important asset in this era as draft picks.
Coleman is on a rookie deal, and while all rookie deals are favorable, he has the contract of the 15th pick in the first round of the 2016 draft.
So................a team that acquires Coleman is assuming his '18 salary, plus if they cut him this year, would also assume a Dead cap hit that includes a pro-rated portion of his original signing bonus. I think Cleveland would have had a cap hit of 3.5 million if they had cut him, Buffalo now assumes this obligation as far as I know. Beyond '18 there are considerations each year remaining on his contract.
A team has to like Coleman and have him fit into their overall cap space this year, plus fit how they project their cap budget going forward while considering all of the moving parts on their roster.
For instance the Browns now do not have a 3.5 million cap hit for cutting Coleman, money they can spend elsewhere, on Dez perhaps. The pick received is a small asset but the salary cap now and going forward saved by trading him was/is an asset too.
The Bills take an interesting flyer but there is more cost than the 7th round pick spent. There are also current and future salary cap obligations which means less money to spend on re-signing current players and future free agents.
When all is said and done, there can be many less suitors for a player in Coleman's situation than one would think. A team has to feel they like Coleman as a prospect, a fit in their system and locker room, fit within their cap for '18, as well as in future years with however they project their roster going forward, etc.
The value of player in the league is inextricably tied to their contract and how both the player and the contract fit into current and future roster plans of each interested team.