The Seattle Sounders custodian has enjoyed one season in America's domestic competition and was impressed by the quality and with new teams being brought in for the next few years, he can see it getting better and better.
"MLS is set up to be a competitive league," Keller said in an interview with ussoccer.com.
"Everybody has the same salary cap, and you can't really go out and spend money to make huge improvements to your team. I think the league is truly moving in the right direction. You have the recent successes in Toronto and Seattle.
"I'm really excited to see new stadium in New York and what that will do for the franchise. The Galaxy are a steady team and have a great facility at The Home Depot Center along with Chivas USA.
"Sure, some situations could improve, but that's the same in every league. For every Manchester United, you have a Wigan Athletic. For the most part, the league is turning a corner, and adding Vancouver and Portland only continues to get us around that bend."
Keller admits his impression of the league was a touch twisted last season as he was in the middle of a frenzy with the Sounders in their first year but was surprised by the amount of exposure the team created in such a short time and is expecting to experience the same again.
"My impression was a little bit warped from the sheer fact of the huge deal that the Sounders are to the city," he added.
"We were happy to be able to reward the fans with a very good season and winning the U.S. Open Cup. Equally as important, we established ourselves as a professional organization on par with the Mariners and the Seahawks. We are not competing with them, but to be on equal footing with those two franchises is something we are very proud of."