What counts as deliberate/active then? If Joe Schmuck plays Injustice in the break room with coworkers, does him wanting to get good enough to at least give the other players a run for their money make him no longer casual?
No. He stays casual because his competitive scope remains parochial.
Let's hash this out now. I think we can come to some standard agreement. "Casual" is as titular and nebulous as they come, but "competitive" less so. I think we can have something of a bridge with the label "enthusiast".
1.
"Casual": Someone without any inclination, or even notion of applying a more structured approach to their gameplay experience.
Competition among friends is enough to satisfy, and the nature of that competition is light-hearted, more often than not. Rarely seeks competition outside their immediate circle. Most do not even consider the notion.
Widest population, but not very gradient in distinction.
2.
"Enthusiast": Someone with a strong inclination towards structured play and dedicates the time and energy afforded to him/her to approaching the limiting "Competitive" ideal/archetype. Utilizes elements in the game like training mode, knows of and adopts competitive culture to some degree, watches streams, reads/participates in message board discussion, participates in local gatherings and tournaments occasionally, and is generally cognizant of expressed and underlying systems mechanics.
Competition is among casuals, competitive players, enthusiasts, online casual/competitive/enthusiast players or some combination of the six.
Medial population, highly gradient in distinction. I think this describes most of GAF and most forum communities, generally.
3.
"Competitive": Someone with a hardline inclination towards structured play and dedicates time and energy well beyond the average towards meeting and maximizing the standards set by the competitive pool. Sociological sacrifices are often necessary. Utilizes elements in the game like training mode, is immersed in competitive culture, watches streams, reads/participates in message board discussion, travels to tournaments regularly, and views intimate understanding of systems mechanics as ideal.
Smallest population, not very gradient in distinction.