I think there are also some altcoins that follow the bitcoin movement, when it goes up and down, but the altcoin average is like that, when bitcoin rises, altcoin is dumped to be exchanged for bitcoin and when bitcoin goes down, altcoin is dumped due to panic. Altcoin average relies on a pump to increase its price, except that the market is bullish.
Agreed. Other things that affect altcoin price (and are not connected with the bitcoin directly) are project development and project's activities. MVP's release, scam accusations, partnerships — the list of possible reasons is pretty big.