Altcoin price depends from BTC price. ETH price also depends from BTC price.
The formula is simple:
Bitcoin falls - altcoins fall
Bitcoin pumps - altcoins fall
Bitcoin stable - altcoins grow
Agreed. But also:
Market falls - new alt on the market will probably has a low price as it "base" support level in the future. Lower than ICO.
Market grows - new alt will have this main support level on higher than ICO price.