After Joffrey Lupul was simultaneously hit from both sides by Philadelphia players Jay Rosehill and Adam Hall on Thursday night, the Maple Leafs forward needed some assistance as he wobbled his way back to the bench. If it was impossible to say what had just occurred inside Lupul’s body and brain on the third shift of just his 10th game of this NHL season, it was far easier to diagnose the presumed condition of Toronto’s hockey fans at the same moment. As their most important player retreated to the dressing room for treatment, his evening finished and the Leafs en route to a 5-3 loss, you didn’t need to be a doctor to know that high-strung members of Leafs Nation had suffered a shudder down a collective spine while a promising season flashed hauntingly before long-suffering eyes. Whether Lupul’s injury is significant or not is a matter for another day. He wasn’t available for comment after the game. And while Leafs coach Randy Carlyle reported that Lupul felt “fine,” pronouncing him “50-50” to participate in Friday’s practice, it was difficult to know what to make of the coach’s assessments. Though no one in Leafland uttered the word “concussion,” Lupul has previously suffered at least a couple significant head injuries during his NHL career. Teammate John-Michael Liles, who missed time last season with a concussion, acknowledged the obvious concern. “It’s definitely scary, just because it’s such an unpredictable thing,” Liles said. “But you hope for the best.” Lupul’s well-being, of course, is inextricably linked to that of his team. The Maple Leafs had been clearly enlivened in the previous six games in which he had been in the lineup since he returned from a 25-game absence with a fractured forearm. They hadn’t lost a game in regulation during the run, going 4-0-2 with Lupul on board. Though he’d also served a two-game suspension, until Thursday night Lupul had scored in every game since his return from his broken arm, racking up eight goals and five assists in those six games. The club had been singing the praises of his contagious presence.