Bottom and middle panels show the distribution of the (α)_LOS parameter for the FP and SP as a function of the dynamical age N_h for all clusters in the sample (gray circles). The upper panel shows the distribution of the rotation differences (α^SP − α^SP)_LOS. The dashed lines represent the linear best-fit to the GC distribution. In all panels, the star symbols refer to the results obtained for the stacked analysis on the dynamically young (green) and old (orange) samples. The size of the star matches the amplitude of the errorbars.