Lou Trivino was ranked 8th out of 8 relievers and very quickly found himself off the roster just six days after publication. That he’s given up just 1 run in 6.2 IP with the Dodgers since then is immaterial. The history of the power ranking does not claim to have any special hold on a player once they leave the San Francisco Giants.
What it has been very good at doing in the past is curse the guy who was fortunate enough to be deemed Most Trustworthy Reliever. Usually, the #1 guy crashes out at some point in the month.