I can't speak for specific numbers, but I can tell you that of my initial class (this time, I'm an Envoy re-tread from '94-'06) was 15 Cadets, and 50 DECs. I was the second most senior in class, 31 years in the industry, behind a 33 year Delta CA who only had 9 months left before he aged out. At the time we were around #2000 on the seniority list. I'm currently number 877, so in 3 years I've moved up 1123 numbers. Of the 50 DECs from my class, a few were like me, coming back from early retirement, but a lot were prior airline FOs who left when covid hit and hadn't been back. 25 of the 50 in my class are still here. So anecdotally, I can't think 9 out of 10 DECs are gone, but 50% of my class is gone. I can't say how many were fired, or how many aged out, or how many got hired at another airline and just moved on. Throughout most of my career, 50% attrition from a class in 3 years would've been considered a huge amount. Today it's different. Some of the overall drive up the seniority list is based on the flow through, some on senior people getting hired OTS at majors, etc. I do know I've heard some of the stories of other DECs who were "weeded out" because of bad habits, attitudes, whatever. I'd say from looking at the list that 90% is a bit overreaching.