Mangini was an NFL head coach for two different franchises, and the Browns hired him after his involvement with Camera-Placement-Gate was well known. He was then a defensive coach (and coordinator) for the 49ers for 3 seasons. However, he's now "out of coaching", meaning he either does not desire (unlikely) or more likely has been unable to secure a job at the NFL or even at the college level for the last 3 years. I find it hard to believe he's just retiring, which means he's either had totally unrealistic expectations of what job he deserves for several years running, people just don't find him all that compelling a candidate... or they want to avoid doing anything that would upset the broader coaching fraternity and Belichick in particular. I kinda enjoy the notion that the latter possibility might have more-than-zero validity.
His middle son's middle name is William, supposedly after Bill Belichick. Bummer for that kid.