Before the U.S. Supreme Court overturned PASPA — but after the buzz about that possibility began — FanDuel and DraftKings were hardly the companies pegged to emerge as the unquestioned leaders in mobile sports betting.

Now, more than five years later — and with hindsight being what it is — their dominance seemed pre-ordained. Of course they would rise to the top. After all, they had a massive database of daily fantasy players, and it doesn’t take a brain surgeon — or sharp bettor — to realize the value of a list like that. 

Clearly, FanDuel and DraftKings’ lists of DFS players trumped the lists BetMGM, Caesars, and other casino-tied operators had of slot slingers and roulette wagerers.

In fact, no other large entity with a fantasy background has yet dipped its toes in the sports betting waters — but that is set to change this month when PENN Entertainment officially launches ESPN BET.

PENN’s new partner, ESPN, has been offering ESPN Fantasy for 28 years and has undoubtedly collected millions of names, email addresses, and tons more information about Americans who have signed up for an ESPN fantasy product.

The big question, then, is simply this: How much is that information worth to a burgeoning sportsbook?

First off, know this: ESPN BET is well aware of the connection between fantasy sports and sports betting.

A source within ESPN BET told Sports Handle that the company has spent “a lot” of time on research, and that internal research shows people who play fantasy sports are more likely to bet on sports, and that this is “one of many levers we’ll pull to maximize awareness of ESPN BET.”

The app, which is expected to launch sometime this month, will have all industry eyes on it. There is widespread uncertainty in the industry, however, as to what effect the fantasy player database will have.

“The short and honest answer is that we don’t know,” said Chris Krafcik, the managing director of sports betting and emerging verticals at Eilers & Krejcik Gaming, a gambling research and consulting firm. 

But Krafcik is wary the cross-sell will be highly effective.

“We note ESPN Fantasy’s season-long fantasy focus and believe season-long players, in a vacuum, likely cross-sell to OSB (online sports betting) at appreciably lower rates than DFS players,” Krafcik wrote in an email. “DFS is a proven OSB proxy form factor; season-long, by contrast, is less betting-infused/betting-forward, with player motivation factors typically more geared toward social elements (e.g., drafting, bragging rights).”

Ryan Sigdahl, who covers the industry as a senior research analyst for Craig-Hallum Capital Group, is also not entirely convinced the fantasy database will yield fruit.

“DraftKings and FanDuel have had great success converting DFS databases into sports betting and iGaming players,” Sigdahl said. “Our caution with making the same assumption for ESPN BET is that season-long ESPN fantasy players aren’t paying to play on the site/app.

“The highest value potential customers in ESPN’s fantasy database are most likely using DraftKings or FanDuel DFS with a funded account already. That conversion to sports betting is a lot easier because you have a shared wallet that already has funds in it. PENN will have to convince them that its app is better.”

At a fundamental level, Sigdahl suggests there’s an even more obvious difference.

“There are lots of ESPN fantasy players that won’t be sports bettors — think office/family/friend leagues — whereas most DFS players are also sports gamblers,” he said.

Lloyd Danzig, the managing partner of Sharp Alpha Advisors, a venture capital firm with plenty of exposure to the gambling industry, wonders if current sports bettors will even consider making the jump to a new app.

“There is no question that ESPN’s database is filled with avid fantasy players and sports bettors,” Danzig said. “What remains to be seen is how much of that audience has already developed irreversible habits and allegiances to existing platforms.”

Of course, ESPN BET has many built-in advantages other sportsbooks won’t have: namely, the ESPN name.

Some observers think ESPN BET will quickly rise to the top of the charts. Others aren’t quite sure that will be the case.

Either way, this $1.5 billion deal, which was signed back in August, has the industry — and mainstream media — champing at the bit to see how this all plays out.

And while very few people are actively discussing this fantasy player database, there is little doubt current — and past — ESPN fantasy users will be hearing all about ESPN BET in the coming weeks.