That's certainly true, mate. Most (if not all) altcoins on the market, follow Bitcoin's price movements. It's expected for ETC to increase in price within every bull market. But I believe that ETC needs to solve its issues first if it wants to go higher in price. Serious investors and traders will continue using ETH above ETC since it focuses on security/reliability above anything else. Considering that ETC is just a copy of the ETH blockchain, it cannot remain on the spotlight for long (unless it starts to innovate). The only difference between both coins (ETH and ETC) is the number of coins that will ever exist on the Blockchain. ETC has copied Bitcoin in the sense that it has adopted a finite hard cap in supply. On the contrary, ETH will experience constant inflation over time as developers kept its supply as undefined. Ultimately, ETH will win above any of its forks since it's the original smart contract platform that started it all.
Whenever ETC is undervalued or not, that's up to anyone to decide. The way ETC is heading right now, doesn't tell us it'll have a bright future. But knowing that crypto behaves in strange and bizarre ways, anything could happen. It's best to keep an eye on the ETC project's development, just in case everything goes back on track. Just my thoughts