Patrick Kane had just scored his second goal of the game to bring the Blackhawks within a goal of a miraculous comeback Sunday against the Edmonton Oilers. It was the third period, and the Hawks suddenly had all the momentum. On Kane’s next shift, he was everywhere, circling the Oilers’ net like a shark, three times striking for a golden scoring opportunity. But the tying goal never came, and the Hawks dropped their second consecutive game. And that genuinely seemed to surprise Kane. ‘‘It was a good comeback,’’ he said of the Hawks’ rally from an early 4-0 deficit in their 6-5 loss. ‘‘But not good enough, I guess.’’ That third-period mentality — that idea the Hawks can hold on to any lead and erase any deficit — was both a cause and an effect of their 24-game points streak to open the season. And just like the goaltending, the defense, the depth and seemingly everything else in this 21-2-3 start, that late-game confidence is quite a turnaround from last season. ‘‘It’s been great that this year we’ve been able to pull those out,’’ Kane said. ‘‘Because last year was a disaster.’’