Ariana's truthfully only underperforming because the single is not top-quality, and mostly because of her over-saturation.
She's had so many hits the past year and a half, that are still good recurrent hits and still played a lot today. Had she waited another solid year, and chose a single better she wouldn't really be in this situation.
Rihanna's been having a 3 year break from her over-saturation, and her singles are still doing terrible.
a good note to end on. Hollering
OMG