Is there a reason for that?
I played some games in CCL recently and it seems, that there are quite a lot of noobs in CCL. This isn't a problem, if the noobs know the difference between CCL and COL and willingly decide to play CCL. However, this doesn't seem to be the case for all: I just had a game against a coach with the sad game history of 2-1-12. He seemed to be rather frustrated with the skill-level of his opponents. Thus, I had to explain him the difference between CCL and COL and warn him, that his team will get banned soon (since he had more than 5 concessions).
Overall, I think it would be better if COL was the first competition in the list to avoid such frustrating moments (games & bans) for newer players.