Interesting point. Here's a though - Newgrounds.com has a similar setup with a ton of submissions on a daily basis. Now, mind you - a good portion of them are not really the best. But either way the last 10 most recent submissions get listed on the home page. 
The site takes in a lot of submissions, but it also empowers its users to vote on games. Games that get a very low rating get buried. Games that do substantially well get voted to the top of the list for the day. The next day, the top 10-20 games that have been voted get listed in a section of the site. Returning users know where to go to play the best games from the day before and the 'Latest' list gets filled with the current day's submission.
The top games for the weeks are reviewed by the staff and they pick the best games for the week to be featured on the home page. This way, the content is always fresh, and new noteworthy games get featured.
Just a thought.