Here are the Beyer Speed Figures for all the Triple Crown races since 1992, the year they were first published in DRF (after first appearing in print in The Racing Times in 1991):
Source: American Racing Manual
Big Brown is the seventh horse in this stretch to be bidding for a Triple Crown. The previous six all ran higher combined BSF's, by 6 to 24 points, in the first two legs:
Silver Charm 115/118 = 233
Smarty Jones 107/118 = 225
Funny Cide 109/114 = 223
War Emblem 114/109 = 223
Real Quiet 107/111 =218
Charismatic 108/107 = 215
Big Brown 109/100 = 209
Now of course, BSF's don't incorporate the fact that Big Brown was restrained down the backstretch and geared down during the final furlong of the Preakness, that he raced wide on both turns of the Derby, that he has made only five career starts, that he has dominated unusually weak competition without being fully extended, and looked magnificent doing it.
Still, interesting.