What's the winning formula? Good question. I don't have a sure-fire answer, but I have some ideas.
As a volunteer, I have been a Hillary surrogate in two candidate forums with more scheduled in January.
People seem to like and respond with interest when policies and issues are treated in depth. It's not enough to say that she has a great health plan, people want to know what the health plan will do and what it will not do. Voters love to hear about her plan to reduce political corruption in DC. Just about everyone knows that she has taken money from Northrup.
Perhaps Hillary's speeches might be a little less off-the-cuff, broad brush and a little more formal presentation of a limited few policies.
Policies are her strength, so perhaps it is time to play up the strong points. Pick a few of the best policies for one speech, and then treat a few more policies the same way for another speech.
She appears to have established credentials as a tough negotiator and attacker. Maybe it's time to assume the electorate understands that and shift the discussion to her policies.
Then, when the rivals counter with their policies, they may be seen as 'me-tooing' it instead of serious candidates.
It might work.