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The Eagles lifted the trophy for the third year in succession with a 91-83 triumph in Birmingham on Sunday, their 25th British Basketball League honour.
Last season the Eagles failed to add to their BBL Cup victory, coming second in the league and Trophy.
"It's a platform, it can spiral two ways," Flournoy told BBC Newcastle.
"We'll enjoy this, because the players have worked hard this first half of the season, but then put it to rest because it comes back to the grind.
"We can't be complacent because we won something, we can go south or use it as an opportunity to go up."
Eagles' victory was inspired by point guard Rahmon Fletcher, who picked up his third MVP award in as many years with a top-scoring 29 points.
"I'm so happy, it's not a cliche, this feels the best so far," he said.
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"If you're too tight, you think too much and can't fall into what you normally do.
"We're relaxed, it's not arrogance, it's the type of people we are and it goes on the court, we're super loose."
Avoiding the same fate as 2016 is a motivation for the Eagles, coming as it did on the back of a four-trophy 'clean sweep' the previous year.
"We got work to do," Flournoy added. "The moment we start saying we were dominant, that will get us in trouble in the BBL.
"There were lots of things we did well, lots we didn't, but we had the momentum, our shots dropped and defensively we disrupted their rhythm."
Newcastle Eagles' BBL Cup final success against Glasgow Rocks is a tipping point in their season, says player-coach Fab Flournoy.