It is difficult to explain the most recent monthly return or year-to-date return and not talk about the long-term average return of the stock market. Many investors have a tough time hanging on during difficult periods and then subsequently reaping the rewards during good years.
With all the ups and downs the market provides, it very rarely returns in any single year exactly the long-term market average.
Part of the value of professional financial advice is understanding the history of investable markets and what investors can expect in terms of both volatility and return. Sound financial advice should stand the test of time in good markets and bad.