The Canadian Junior A represents a lower tier of junior hockey. It is situated right below the three major leagues of the CHL (QMJHL, OHL and WHL) in terms of competitiveness, and is made up of players who are not yet good enough for the level above, but also of individuals who choose not go the major junior route, wanting to pursue NCAA hockey.
American colleges forbid any prior pro experience for their players. The CHL falls under that category. Thus, the competitive level of Canadian Junior A is improved by the presence of some players who would be, without a doubt, contributors in the CHL, but who can't play in the league due to NCAA rules.