IMO, a new cast member should be exactly that: new. And the character should be introduced as such. That's something I believe was a mistake that the powers that be made with Laurence Fishburne. It's fine to hire an actor with his credentials, but you can't expect your audience to just immediately accept him as the primary focus of attention on a beloved team that's been intact for years. So the new person should be introduced slowly, gradually finding his or her place within the team (just as any new person would in the real world).
Don't get me wrong; I like Ray, and I really like the way he was introduced. It was such a novel concept (at least, for network TV) to have this character, a longstanding professional in different fields, but not forensics. They should have continued having him be the student, not the teacher, and flesh out the conflicts that would create for someone of Ray's background, rather than fast-tracking him into a leadership role, as seems to be the case. As I noted in another thread, Fishburne is a fine actor; he could play the complexities of a lead character who's not in a leadership role. But there seems to be a lack of imagination on the part of the powers that be (which extends to the writing team, since they take their marching orders from the producers) on how to make that happen, and do it in a believable way.