Beyer speed figure question

I notice in the 9th race at SA a horse named Privalged won a race on FEB 19 2011 going :20.8 :43 :55.6 1:08 and he only got an 87 beyer. He was no more than a half length off the lead at any time during the race. It was also on a wet track. Can someone explain to me this low figure?