The 2011 Stanley Cup Finals between Vancouver and Boston was certainly one of the strangest in history. It produced the worst Plus/Minus number by a player who sucessfully got to the Cup Finals. In truth, Canuck Christian Ehrhoff merely tied the record of -13 set by Luc Robitaille in 1993. Ehrhoff played 23 of Vancouver's 25 games on his way to equaling the unwanted record.
Canuck captain Henrik Sedin checked in with a -11 mark which is the second worse rating for a Cup Finals participant since +/- became an official statistic. The only two other players to make it to a Final while sporting a -10 rating was Florida's Scott Mellanby in 1996 and Boston's Don Sweeney in 1990.
How rare is it for a player to get to the Finals and have even a -7 rating over the playoffs? Since 1984 it's been done by only 13 players.
If the threshold is raised to a -5 rating, even that is a rare number for a player who made it to the Cup Final. As some solice for the five Canucks who were at least -5 last year (Oreskovich, Glass and Daniel Sedin the others) there have been some big name Finalists in the past that were saddled with a poor minus. In 1984 Denis Potvin and Bobby Nystrom of the Islanders both sported -5 ratings enroute to a Cup loss to Edmonton. The following year Flyer Peter Zezel also went -5, then Calgary's Joel Otto did it in '86. Of course all of these lost the Cup. In 1991 Brian Bellows had a -6 and Bobby Smith a -5 during the unsuccessful Minnesota Cup run.
In 1992 Pittsburgh's Jiri Hrdina somehow clocked a -6 rating in "helping" the Pens to a Cup win. Rob Niedermayer is the only player to have done ths more than once. In 1996 for the Panthers he was -8 and in 2003 for the Ducks he was -5, his team lost the Cup in each of those years.