A decade ago, fast-casual concepts were still novel enough that their very entry into a market could draw long lines and buzz. But as the category has matured—and an onslaught of competitors has emerged to contend for Americans’ dining dollars—customers now have the luxury of being particularly choosy when frequenting fast-casual restaurants.

It’s left some to wonder whether fast casual has reached a saturation point—whether its tremendous growth has finally found its ceiling.

“It is a harder space to play in these days, no doubt, because there is more competition,” says Zach Flanzman, chief strategy officer of Chicago’s Brown Bag Seafood Co. “Ten years ago, just by merit of being a fast-casual player, you had tail winds at your back to help you grow and succeed.”

This new reality doesn’t spell doom for the category, Flanzman says. But it does require operators to offer a strong differentiator and increasingly seek operational excellence. The four-unit Brown Bag, which offers cooked seafood options, recently opened its fifth Windy City location.

In the coming years, Flanzman expects to see continued reshuffling in the space. “I think we might be entering an environment where we shouldn’t be surprised when some restaurants struggle,” he says. “It’s a higher bar.”

There have been red flags in fast casual ever since Chipotle’s E. coli and norovirus outbreaks in 2015. But those red flags became more apparent in 2018. Upscale hoagie chain Taylor Gourmet abruptly closed all 19 of its stores last September after an investor pulled funding. Two months later, Honeygrow announced plans to close five stores and put the brakes on plans for future expansion.

Those closures came amid a cool-down in the overall restaurant space. Market research firm The NPD Group counted 660,755 total U.S. restaurants in spring 2018, a 1 percent decrease in the unit count over the previous year.

Fast casual still remains an industry leader. It was the only quick-service segment to post year-over-year traffic growth, according to NPD research. But that growth has slowed as unit expansions have decelerated; while fast casual visits grew by 8 percent in 2014 and 2015, growth fell to 3 percent in the year ending December 2018, according to NPD data.