Can any experienced traders comment on the rreliability of an increase in volatility brought on by movement in one direction offsetting the price decrease of the opposite direction long option? In other words, does an increase in volatility brought on by a sharp jump in price cause puts to not decrease in price as much as would be expected if the same movement happened more slowly? Also, is the market rationalin that what applies for the above also applies to a sudden drop scenario and its effect on calls? I'm curious because I know there is more of a rebound effect for down gaps in underlying price than there is for up gaps. Still, options traders a more calculating so . . . where does that leave us?
Your question is worth looking at from an academic perspective, and the answer in general is yes. But in reality there are many variables that can impact the option price at a point of exploding volatility, two of the most important being delta and time to expiration.
That leaves us with a systematically tradeable event, but one that depends on the fine-grain level of the options -- strike price as a % of underlying -- and/or, how close/far in time. Smooth mathematical functions (stemming from lots of time or many listed strikes) can get plenty stair-stepped as things compress, and then we should *expect* to see the anomalous results you describe.
If we see a jump in IV as a result of what the market will now pay for said options, depending on how near the money it is and time to expiration, yes you're going to see an increase in option value (and vega focuses on this). If you're looking to specifically target this, then you need to be hedging delta out of the equation otherwise you either need a lot of time left or a shitload of volatility.
The answer is almost certainly "no". With rare exceptions, the increase in vega will not offset the delta losses. The exceptions that come to mind are really low delta options, the ones that are either far OTM or marked at a very low vol. Also, it could be true for products with extremely high volatility of volatility such as VIX.
Not reliable at all... the reaction of Implied Vols is related to the real underlying move AND to what was expected. IV is a reflection of the volatility now and immediate future... partly based on historical vols. So, if there's a sharp move down... it might result in a drop in IV, when that move (or a bigger move) was expected. Same goes for up moves. You see this especially in single stocks, less in index. If something is brewing, either on a not exact know date, or on a specific date like earnings release... the IV will be up to reflect the expected higher real volatility, but drop after the fact... since the event has gone. It's a little bit like "buy the rumor, sell the news". If however the event which causes the move wasn't expected and it's significant in increasing risks... the IV will rise and some OTM options might keep their value or even increase due to vega-effect, while the underlying move is against the option. But I don't think you can really point it down. The opposite can happen just as easily with very high IV's. Skew is more fluid than you would think, especially in single stock options.