It is premature to say the single is not helping the album sell. We are in January; none of the albums are doing great. Pretty much everyone bought albums in november and december. Selena sold more than 120,000. Of course she's going to show a drastic decline in the beginning of the year. I'd wait for february before saying whether or not LYLALS is helping the album.
And Gerry had a feeling the song would be huge; it happens. Adele had a feeling SLY would resonate with people. No need for having proof to support a claim of intuition.