I think Maroon was sent down because they are auditioning players for the 2nd line, and potentially for the 1st line next year, and using the 4th line to do it. Thus far, nobody has really shown anything, which is why they probably keep juggling.
I'm not saying I agree or disagree with it, just that it seems to explain the rotation.
hm.. i donno, maroon has shown that he could be good. he has the hands for top-6 and the size/skill. Just not sure about the speed