IF THREE is a trend, NHL goalie coaches are on the brink. The rule book says, "If both listed goalkeepers are incapacitated, that team shall be entitled to dress and play any available goalkeeper who is eligible." That was the case last Saturday when Bruins backup netminder Niklas Svedberg stepped in for Tuukka Rask, who exited with a migraine in the second period of a 4--2 win over the Rangers. That left no sub for Svedberg, so, after shedding his suit and tie in a Clark Kent quick-change, goalie coach Bob Essensa, 50 (above), paced the Bruins' bench in full pads and a jersey some 13 years removed from his last start. Three weeks earlier Panthers goalie coach Robb Tallas dressed as Florida's emergency goalie in a 3--2 loss to the Leafs. Neither coach ended up taking the ice, which in the Bruins' case was a good thing, laughed head coach Claude Julien: "What a joke."