Found this whitepaper in the "Financial Advisor" section of Vanguard's website
"Putting a value on your value: Quantifying Vanguard Advisor's Alpha"
https://advisors.vanguard.com/VGApp/iip/site/advisor/researchcommentary/article/IWE_InvResValueAdvisorsAlphaIt outlines a strategy where advisors can help their clients not by trying to beat the market, but by doing the following:
Asset allocation
Choosing low cost investments
Rebalancing
Behavioral coaching (don't jump out when the market crashes)
Asset location (what to put in taxable vs. tax-advantaged accounts)
Withdrawal order
Total return approach (take capital gains and dividends)
They sum up the benefit from each of these and come up with a 3% benefit, by which advisors could justify their fees.
My perspective is, "Do It Yourself!" But this is still a good guide.