Eight months after Manny Pacquiao handed him his first career loss in a unanimous decision, Timothy Bradley (31-1, 12 knockouts) returns to the ring on Saturday to face Diego Chaves (23-2, 19 KOs). Bradley is the overwhelming favorite to defeat the hard-punching Chaves, but, if history is any indication, there should be cause for concern. Most of the elite fighters Pacquiao has beaten over the past decade were never the same afterward. The list includes former world champions, almost-certain future Hall of Famers and once-promising prospects who never won another meaningful fight.

In Pacquiao’s past dozen fights against foes that have held at least one world title belt before entering the ring, opponents came into the bout with a combined record of 532-35-4 (.935 win percentage). Afterward, their collective record was 49-26 (.628).

Some have bucked the trend. Juan Manuel Marquez earned some of the greatest victories of his career after fighting Pacquiao to a draw in 2004—the first of four fights they had against each other. After Pacquiao won decisions in 2008 and 2011, Marquez knocked out Pacquiao in the sixth round in 2012. Miguel Cotto has also rebounded nicely after Pacquiao stopped him in the 12th in 2009, currently holding the WBC middleweight title.

But after taking eight rounds of punishment in 2008, Oscar de la Hoya—one of the greatest champions of the past two decades—retired. Ricky Hatton, an international star brutally knocked out in the second round, stuck around for just one more post-Pacquiao bout. Erik Morales was never the same after beating Pacquiao by decision in 2005. He went on to lose seven of his last 11 fights, including two rematches against Pacquiao.

Though he never won a title, Emmanuel Lucero was a rising prospect with a shiny 21-0-1 record before battling Pacquiao in 2003. After Pacquiao demolished him in the third round, Lucero lost 14 of his next 19 fights before retiring.