But I understand that google has a very flat management structure (I have heard of 1 manager per 100 geeks). If that is true, you probably do need some kind of

But I understand that google has a very flat management structure (I have heard of 1 manager per 100 geeks). If that is true, you probably do need some kind of systematic examination - you don't have another choice. My group has 7 geeks, I know them very well and can anticipate them quitting better than any damn algorithm, even for personal reasons (though not always for indirect personal issues, like "my wife wants to move back near her family").