Suarez made these observations at the annual Weitzman DFW Retail Forecast. He said Walmart had become simply "good enough" over the years, a situation that started turning around in 2014 when Walmart promoted Greg Foran to U.S. CEO and Doug McMillon to systemwide CEO. “Greg was the first one to tell me that the stores weren’t good enough and that they had to get better,” Suarez said. Indeed, Foran saw that many good retailers were disappearing from the retail landscape. Suarez recalls Foran’s thinking at the time: “Good enough is not good enough anymore — you have to be great,” Suarez said, citing Foran.

It was clear to both CEOs, Suarez said, that customers, not the retailers, were dictating where, when and how shoppers wanted to shop, Suarez said. In 2011, customers were so frustrated with Walmart’s initial online-order pickup program at stores — including 22-minute-average waits — that they “abandoned the experience 15 percent of the time,” even if they could see their goods sitting right there behind the counter, said Suarez. The retailer told customers little about the program other than that it existed, he said. Nine years later, the average wait time at the retailer’s pickup towers is only 11 seconds, Suarez said.

Read more: How Walmart is revolutionizing grocery shopping

Walmart also set out to improve product quality, particularly in produce — the top factor when consumers choose a grocer, Suarez said. “Grocery sales account for 56 percent of Walmart’s total U.S. revenue,” he noted. Suarez himself oversaw the introduction of curbside grocery pickup at 3,200 Walmart stores. The company underestimated the popularity of that service at the outset and thus has to expand the technology and the square footage to accommodate it, he said.

The retailer also launched the app-based InHome Delivery system, through which store reps deliver groceries direct to customers' refrigerators. Customers have responded, and Walmart continues to gain market share. Walmart has discovered that shoppers tend to use a combination of pickup, delivery and in-store visits.

Walmart remains in a continuous state of experimentation. The company is testing out cashierless stores, and its in-store veterinary clinics are on track to exceed 100 in number by the end of this year. Walmart is even toying with sales of beer for in-store consumption, Suarez noted, and a few stores are bringing in Starbucks units fitted out with dog parks.

Suarez predicts that self-driving cars will help streamline Walmart home deliveries in the near future, with customers dispatching such cars to pick up their goods. That will be a game changer, he said, if it is executed correctly.