Alot of the key factos has been mentioned above, but I miss maybe the biggest reason for, atleast, Detroits late round success.
Its certainly valid to mention that Detroit themselves passed on these kids, and natrually were higher on other players who turned out to be busts.
But, you gotta keep in mind the types of players Detroit has drafted round after round year in and year out.
At a time were teams wanted size and character guys Detroit took the most skilled/best hockey players available, basically.
-They have never been intanglibles horny. Like you so often hear stuff like "This kid is 6'4, he can skate well for a big man bla bla bla bla" with Detroit, instead they take that kid who just had a very good season at whatever level he played, they take that player who is able to get it done.
-They have looked at the right places at the right time. Which is very very very important. Developing hockey players takes know how. A country like Canada will sometimes develop some good players or at times a big majority of all good players, depending the state of their programs. But countrys like Sweden, Finland, the Czech Rep, even Russia, is alot more streaky when it comes to developing kids. If Sweden's program is behind Canada and the US' programs, we won't develop more than the odd decent player like every other year. We have seen that for long stretches. Look at like players born 81' to like 84' from Sweden in the NHL, you have like Kronwall in the NHL, Alex Steen, and a few others, but certainly not many or that good. While at other times, Sweden can develop like a 4-5 very good players per year. The diffrence can litterary be counted in several hundred per cents.
-And of course how they are developed. Kids are drafted for roles in the NHL, and there is never any doubt what is expected from them or what roles they will get.