Michael Kranish notes that Super PACs might have flubbed in the general, but they seemed to be particularly effective in certain contexts.
....the evidence is that super PACs and related groups can deeply influence hotly contested primaries and campaigns in which a candidate is relatively underfunded.
.... In the same way, backers believe super PACs have been more effective in primaries and general election races for the US House and Senate as well as for state legislatures. Challengers in such races often have limited resources, in part due to limitations on campaign contributions.
[Hat tip: Rick Tyler]