Performances of maxBCG richness (left-hand panel) and of Planck Y_SZ (right-hand panel) proxies. The plots compare the richness- or Y_SZ-predicted masses vs. the caustic mass for the very same sample used in Fig. 3. The solid line is the one-to-one relation (not a fit to the data). The dotted lines show the above line plus or minus the claimed mass precision (left-hand panel) or our richness performances (right-hand panel) for comparison with Fig. 3. The (red) ticks on the ordinate of the three panels indicates unmatched clusters.