The thing is, Gordon Hayward is the "Tom Brady" of Utah, and so he can make a much bigger name for himself as an all-star in Utah which doesn't have an MLB, NHL or NFL team either lol.
He would be more of a #2 or maybe even #3 guy here in Boston (#3 in a few years assuming Fultz and Brown pan out too).
I'd love to have him but I wouldn't be surprised if he stayed with Utah as well.
Boston's market is bigger but it's not as big as say, Miami or Golden State (risers), or NYK and LAL. It's more on the "lower end of Top-10", so like 8-10th biggest market in the NBA I believe, although Forbes has it valued like 4th best I believe. I'm thinking more popularity and TV ratings though. But if BOS can contend real soon and build a "super team" it will rise as well.