I have seen LoL channels with little to no effort put into them, with no commentary even on their video with millions of views monthly...I disagree but not completely.
Yes it is based a BIT on luck but not cometely.
He must have posted some very good content at the right time which made his channel grow.
Otherwise there are a lot of LoL channels who post regularly and still dont grt any traffic.
He must have posted something great and after getting traffic, he can continue pisting avg content once in a while to be active and still get a lot of views because of his sub count.