Great article. Just wondering your thoughts about "returns based style analysis"? There is a website called www.styledriftscorecard.com which shows style drift over time for every mutual fund. You can then see which ones are drifting or not.

Also the question on target date funds, I found a target fund, for example, that was a 2020 target date fund but it's best fit index was a 2030 target date index. Which means they are assuming more risk than the 2020 target date fund should be assuming. You'd have to look at the data yourself and you can check on the fund.