In Today's TDN:

TDN's Bill Oppenheim takes a closer look at Beyer Speed Figures and the Triple Crown series. “Though there is a general correlation between racing ability and a horse's prospects as a stallion, the correlations are far from direct. In other words, just because a horse ran big Beyer numbers doesn't guarantee he will be a successful sire, nor does the fact a horse doesn't run big Beyers mean he definitely won't be a good sire.”