I wound up clicking on a link obnoxiously named "Grit: The New Killer App" thanks to a coworker. Good news, guys--grit has been defined through research! Not sure if you're gritty? You can take the test!
Note: this actually has nothing to do with baseball, and the paper is a few years old, but I thought it might amuse some of the readers here--chiefly because it's a research paper that talks about a Grit Scale and contains actual sentences like "It may be that each successive generation of Americans, for social and cultural reasons, has grown up less gritty than the one before."