Email from David Craig observes:
Usually this phrase is used to mean there's no room for improvement. In this case it's quite the opposite. 52 seconds in to this recap of yesterday's Cubs Nationals game.
Here's the phrase, in a bit of context:
Five nothing Cubs, bottom five: It doesn't get any better for Jordan Zimmerman, as Dioner Navarro comes through with two men aboard.
Jordan Zimmerman is the pitcher for the Nationals, who has already given up several home runs, and at this point — the bottom of the fifth inning — gives one up to Navarro, the Cubs' catcher.