Hmmm. Keeper or not, that seems like a lot to give up. Obviously, if it's a keeper, there's no way that you can make this deal. However, if you're that starved for speed... maybe. Let's see.
Firstly, what speed options are available on the WW? Rajai Davis might have been dropped after losing playing time for a bit there... but he's back for as long as Conor Jackson is on the shelf... and Coco is not the most reliable injury-wise. He could give you the same sort of speed boost for the price of a drop. What about lesser speed options like Roger Bernadina, Coco Crisp, Jose Tabata, and Fred Lewis?
Anyway, on to Chone. He's batting .235/.332/.276. He's striking out more than he ever has in his career before. To boot, he's been just as bad recently as he has the rest of the year and for a speed guy he only has 38 runs. His babip is lower than it has been for his career, but at .291 it's not like it's abysmally low to match that abysmally low batting average. Still, he does have 24 steals, which is pretty nice.
In short, while the stats don't offer much hope, he is a proven veteran and it's never smart to count them out. I think he'll rebound, but to expect a .300 BA from here on out would be irresponsible. I'm thinking somewhere more in the .275 range, unless he's able to cut down the Ks. The thing is, Heyward, once he comes back, has the talent to be a top 10 OF from here on out... and should at least be top 25. Find the guy in your league that's obsessed with youth/ prospects and see if you can't get something better there.