Due to a mix of fundamental and technical factors, I believe the price of ZEC has bottomed relative to ETH, which may lead to substantially higher ZEC prices in the near future.
Currently ZEC has relatively little use outside of speculation, which results in periods of intense demand and rapid price increases. Demand is particularly strong following news about ZEC, such as new exchange listings, but this demand eventually drops off when ZEC falls out of the news cycle. This demand imbalance means that the overall supply and demand dynamics of ZEC are particularly sensitive to miner activity, and whether the amount of newly mined ZEC being sold is greater than or equal to the current demand for ZEC at market price. An excess of supply at the current market price naturally leads to lower prices.
Miners are motivated entirely by profit, so their motive to sell ZEC must logically be incentivized by profit. GPU miners in particular have been known to switch between mining different algorithms in order to maximize their returns. Historically, AMD cards achieved their highest returns mining Ethash, while Nvidia cards achieved their highest returns mining Equihash. Miners with 1080ti's who wanted to accumulate Ether were better off mining ZEC and exchanging it for ETH, resulting in selling pressure on the ZEC/ETH pair. Due to the recent increases in Zcash network difficulty this is no longer economical and thus a significant source of selling pressure has disappeared.
Miners who accumulate coins rather than sell them may also be shifting from ETH to ZEC, as seen in the ZEC/ETH trading pair. The trading pair has been in decline since Zcash's inception, from highs of over 200 all the way down to 0.42 today. Miners who did not immediately sell mined ZEC for ETH (or BTC) missed out on huge profits. However, this trend may be coming to it's conclusion.
Looking at the ZEC/ETH chart, a large falling wedge pattern has formed over the course of the last 16 months. The pattern is well defined with no less than 5 reaction highs and lows, in addition to consolidating volume. The pattern saw a false breakout to the downside in January reaching a low of 0.33 on February 1st, followed by a strong move back above 0.5. The new low was tested in May, reaching 0.347 on May 13th, followed again by a quick move above 0.5 on huge volume. This event marks the breakout of the falling wedge pattern. Since that date, the trading pair has fallen back to test the upper trend line of the wedge, and has made what appears to be a triple bottom formation at 0.35. This pattern will be confirmed with a strong move above the 0.50 level on increasing volume.