I look at it from a different perspective. Instead of specific turning points I just see really bad drafting in every single year from 2008-2013. That's six consecutive years of bad drafting.

Secondly - while it definitely takes time to overcome the damage done by that ^ there were other contributors. The biggest were the decisions by Khan and Caldwell to hire Bradley and then to keep him (at least) a year too long.
Caldwell's over-eagerness to gut the roster and "go young" cost the team a bit as well, but it was a much lesser sin than those Gene drafts, Caldwell's first draft and the Bradley hire.

---