IMHO, the problem with many rebuilds is that they try to change the players without rebuilding the organization as a whole, i.e., management, coaching staffs, data analysis, etc., and so what they end up with is a collection of new players in a flawed system.
Success usually starts from the very top; so does failure. If the last rebuild failed, the next rebuild is also likely to fail unless you flush the system as a whole. See, e.g., Jerry Jones' Cowboys.
A problem is that ownership builds relationships with the organization that they trust, but then hold on to those folks out of loyalty even when they have passed their prime. The organization thus ends up with a bunch of dinosaurs trying to do things that might have worked two decades ago, but no longer work now. New thinking required.
This is not to say that rebuilds are not necessary -- every organization goes through them periodically -- but that a good rebuild is much more than amassing younger and better talent. Rather, a good rebuild is a fresh start from top to bottom.
My own take anyway, Viva La Difference!