Complex sentence: After the third slowest start in Belmont Stakes history, they raced the fastest last mile in Belmont Stakes history, and finished in 2:26 4/5, the third fastest Belmont, at the time, behind Secretariat and Gallant Man.
Split into simpler sentences: After the third slowest start in Belmont Stakes history, they raced the fastest last mile in Belmont Stakes history, and finished in 2:26 4/5. It was, at the time, the third fastest Belmont ever, behind Secretariat and Gallant Man.