A top competitive gaming team has welcomed Mike Sepso, an esports veteran and former Activision Blizzard senior vice president, to its roster, underscoring the sector's surging growth.

The New York Excelsior (NYXL) revealed Thursday that Sepso, co-founder of Major League Gaming who recently left Activision Blizzard, had joined NYXL. The Big Apple based esports team is backed by Sterling.VC, a venture capital fund, and an arm of Sterling Equities, which also owns the New York Mets. The NYXL is one of the original 12 teams in the Overwatch League (OWL).

Sepso helped craft and launch the league, based on Activision's megahit shooter game "Overwatch," during his three years with the company while overseeing commercial partnerships for its esports division. OWL's global city-based franchise structure is still the first of its kind and, according to Sepson, among the "biggest achievements" in esports to date. It comes at a time when game publishers and independent companies are diligently experimenting with their own competitive leagues.

"Many people spend time trying to work out how to build the perfect structure for esports," he told CNBC. "We got it mostly right, and what that led to was an opportunity for the league and individual teams to be successful."

But Sepso ultimately believes it is the commercial success of OWL and its individual teams that has been a "massive boon" for esports. Intel and HP both threw their weight behind the league before its inaugural season, with T-Mobile, Toyota and Sour Patch Kids later rounding out the big corporate sponsorship deals.

Activision then signed a multiyear broadcast deal with Disney and ESPN that began with live coverage and streaming of July's inaugural "Grand Finals."

Sepso is no stranger to the commercial side of esports given his history pioneering many of the first major deals in the industry. With current Activision executive Sundance DiGiovanni, he co-founded and oversaw Major League Gaming. The professional esports organization convinced the likes of Dr. Pepper, Old Spice and more to become some of the first big brands to dive into esports in the years after its 2002 launch.

During MLG's near two-decade history of tournaments, its "Halo 2 Pro Circuit" also became the first televised console-based gaming league in the U.S. in 2006. Seven years later, the company launched its own streaming service, MLG.tv.

Activision acquired MLG in January 2016 to the tune of $46 million, just months after Sepso joined the gaming giant in his executive role.

"It was an amazing time [to be at Activision] in the three years I was there," he said. "It was incredible in terms of the dramatic change happening in esports, and getting to be one of the architects" behind the building of a new esports business, he said.