There certainly ways to manage it and obviously some do, but I think people overestimate the importance of large markets to branding and endorsements. Michael Jordan's agent agrees:
"Falk: In 2012, I find that to be incredible that someone would think that. We live in a digital age, and I think people like Dwight Howard, LeBron James, Kobe Bryant, Dwyane Wade, Kevin Durant -- Kevin Durant is incredibly marketable in Oklahoma. He doesn't have to be in New York or L.A. I think he could be the best player in the league in two years, at the most. And if someone said to you, "If you represented him, would you move him to New York?" I'd say, "No, for what? I think he has a certain homespun credibility being in Oklahoma. It's like Brett Favre being in Green Bay." And I think these guys are being told by these agents who aren't very sophisticated in marketing that you have to be in New York or L.A. to be marketable. Maybe they've never heard of the Internet."
https://www.si.com/more-sports/2012/03/02/david-falkqa
Now that's for the superstars. What about the midrange guys? I think it is even more true. Meram, Afful and Trapp can probably do TV ads and billboards for auto dealers or local restaurant chains in Columbus. Same for Martinez, Gressel or Villalba in Atlanta. In NYC? 95% of the city has no idea who Ring, Chanot or Callens are (hell, 80% probably has no idea who Villa is) and their marketing worth is close to zero outside of sports-related opportunities (Modells, etc.). For those types of ads it is better to be a big fish in a small or medium pond than a nobody in the biggest media market in the country.