Is this a Good Trade?

Yeah man, I'd actually do that to be honest. Ryan Matthews has been such a bust this year (I'm sorry you even have to deal with him- I hate the Chargers, i'm a Broncos fan ahah). Anyways, so has Forte (as he's really only had one stellar game). Chris Johnson on the otherhand, i'm sure i don't have to say anything about him as his stats speak enough. You also have Marshawn Lynch as a running back which I like in Seattle, he's going to rack up some touchdowns every week for you and should be a nice #2 back on your roster. Do it up son, and let CJ run wild!