There's an error in Federer's results listed on your site, impacting his ELO. He didn't lose to Steve Johnson at Halle on Tue Jun 10 2014. See the official draw/results:

http://www.atpworldtour.com/share/event-draws.aspx?year=2014&eventid=500&draw=ms

Steve Johnson beat Albano Olivetti 6-4 6-2, rather than Roger Federer.

Perhaps there's a problem with your data feed? I wonder if the same feed has caused other errors too. You might want to check.

Otherwise, great site, thanks!