That's a really weird result. You might think it could be a VRAM issue, where the games tested at settings where 4GB isn't enough for the 290 but the 380X gets by because of color compression.
https://www.techpowerup.com/reviews/ASUS/R9_380X_Strix/1.html
It could be the new mix of games, but in the 380X review the ref 290 is 27% faster @ 4k then the overclocked Strix model. It wins every single game benchmark.
Unfortunately they don't have the 290 or 380X in the individual scores of the new Matrix review, but if you look at the 390X in the common games between the two reviews, the scores don't change. It doesn't seem like different settings between the reviews.