In the past 18 years, MLS has risen from strength to strength with the addition of big-name players from overseas but Arena believes it can become even better if there is more emphasis placed on nurturing promising local youngsters.
"There aren't as many peaks and valleys as there used to be. The line has flattened a little bit, which is good," he said in an interview with the Washington Post.
"Now, you want to have a steady rise. In the last decade, boy, there have been a lot of ups and downs. It's gotten better, but there is still a lot of work to do in every area.
"We still have a league where we don't appreciate the assets we have in this country, that our players are much better than the league gives them credit for. This league should continue to be about the American player.
"The league overall is doing great. There is not anyone who doesn't think the league will be around in 10 years.
"Ask that question 10 years ago, there would've been some doubt."