Bitcoin Cash is just another alt. It has no more or less bearing on things than any other major coin. Almost all of them regularly post higher gains than Bitcoin percentage wise because they're all smaller.
2018 is nowhere near the worst year yet.
The one and only reason for these lulls is that giant bubble that you might have noticed. Bubbles pop when enough people realise they stupidly overpaid for something and run for the door. It takes a long time to rebuild confidence in valuations once it's been torched like that.
I don't think size really matters, It's not just an alt, it's competing with bitcoin, with intentions to take the throne and the name is similar. Market cap isn't too small either. Let's not forget there is lots of manipulation in the market and maybe whoever cares about bitcoin being always on top doesn't want to give it any chance. Anyway in my view it's cancer that needs to go away like the other pretender BTG, first slid out of top 10 and then top 20
Competing? I cannot see any competition here as far as I am concerned, and if you think it is by manipulation of price based on its growth in value, then I must say you must have underestimated Roger Ver and the huge position he had in bitcoin which he must have moved into his own alt.
Bitcoin cash was never a problem to the growth of bitcoin and by the way, even bch is really feeling the heat of the market as well presently. BCH is never a threat to bitcoin and if that is what you think, then, you are really mistaken. By the way, I like how you called BTG pretender as that is basically all these forks are including BCH and they really have nothing to offer.
I expected you were going to say the cancer in our midst are the CME and CBOE that came up with the future contract and seems more like the market is having the hand of the biggest manipulators in the industry. However, 2018 is still going great for those who understand what the future holds.