One other thought in this drama. Why did Joyner feel dissed in the first place? Instead of convincing Him to stay with a story about some old QB Lamarcus has never heard of why not have the talk before camp if why he's important to the team and why Fish considers him a starter?
Something like, hey Lamarcus, Coach Fish here, just wanted you to know we're signing a CB today. We think he'll help us outside with Tru and Gaines. Now, the reason I'm telling you this is because you have a much bigger role here. You are my inside guy. Tough job but you are the best at it. It's starting job and the reason we traded up to draft you. In camp we'll get you reps outside and at safety in case of injuries, but you are our starting nickel and I'm looking forward to seeing you thrash.
Letting guys know their roles is very important. If players see what ur is you want from them then they can be successful. Not sure this is Fish's greatest strength.