Box-and-whisker plot of the rotation rates of 26 SPB stars obtained from averaging over eight theories of core-boundary and envelope mixing by Pedersen et al. (2021). These are grouped into the two classes defined in this work: low and high f_sv, as indicated schematically on the x axis. Whiskers are extended past the quartiles by maximally 1.5 times the interquartile range. Outliers are indicated with a rhombus mark. Individual rotation rates and estimated standard deviations are indicated in grey. The horizontal offset for these rotation rates is imposed for reasons of visibility, without any additional meaning.