at least according to MS-NBC. Andrea Mitchell announced it in remarks before the memorial service in Dallas.
Stavrides is a ‘76 Naval Academy graduate, with a Ph.D. in International Relations from the Fletcher School at Tufts University, of which he is now the head. He headed both Southern Command and also served as Supreme Allied Commander Europe, I believe the first Naval officer to do so.
He has tons of decorations and had a fairly distinguished career: it is rare that one person heads two different regional commands during his career.
He is very much an advocate of “smart power” which he describes as a mix of hard and soft power taken together.
He is well-known as an author, and frequently has appeared as a talking head on TV.
You can get a good sense of him from his Wikipedia entry