The Premier League club bounced back from a five-game losing streak on Saturday with a 3-0 home triumph over Everton, with Long setting up Graziano Pelle for their second goal.
Southampton were second at the end of November, but four straight top-flight defeats, plus a loss in the League Cup, sparked plenty of speculation Ronald Koeman's team were on their way down.
But nothing could be further from the truth, according to Long.
"Lots of people don't have a clue what they are talking about if they think our bubble had burst," the Republic of Ireland striker said.
"If they had seen the games, they would be happy with the performances.
"You'd be disappointed with the results, as we were, but we knew if we kept doing things right it would turn our way and we'd get that rub of the green eventually."
Southampton will look to build on their impressive win over Everton when they visit Crystal Palace on Boxing Day.
