Jumpbot drops

if I could banish one thing from existence, it would be orbital jack drops. Not quite what you suggested in this post, but still hearing "jumpbots" and "drops" makes me irrationally angry. And of course, as soon as anyone says orbital jack, someone has to go and twist the knife and say "just build flea/gnat lol"

Pure metal cost effectiveness isn't the only thing to be considered. First off, jacks usually target singus, so that lowers overdrive which means less metal produced, which can be significant. Next, it can also be a huge hit to moral, since a team who's pushing forward on mid, they've got overdrive set up, things are looking good... then the jack tide starts. You've got an endless stream of these immensely tanky and high dps assassins that can reach any part of your backline, singus are blowing up, nothing is safe anymore, its utter pandemonium with people trying to build gnats, fleas, ravens, faradays, pickets, and none of it working. Add to this fact is that usually the amount of jacks ramps up quite a lot, so you might have 3-4 jacks sent every wave, and that guarantees something is blowing up. And again, this is 1 jack player, demanding a response from usually 2-4 players. This means 2-4 players apm, metal, and units no longer doing something on the front or making something useful, and instead creating a porctress in vain in the very back of their base which is never a good thing. It's all very frustrating.

katastrophe
https://zero-k.info/Battles/Detail/1748338
i think this is good example of jacks drops being game changing move (kind of).
Using this game as reference i want to show why i also hate jack drops and expand a little Nighthawk44 comment that i agree with.

At 24:05 jack drops started, at 25:55 ended, + 1 more jack drop at 33:43
Team south was jack droping
total of 6 jacks and 9 newtons (5400m) kill 1 singu (4000m). Not cost effective? Important thing is how both teams react to that play.

First: the front was stalemate. With attrition around 120% for team south but better eco (56k to 39,7k) for team north. None was really winning. But some time after (around 37:00) south got upper hand. Obviously there might be many others reason to that but as Nighthawk pointed ppl attention and resources are split between front and back and that increase chance of some mistakes (happened to me personally all the time if i am the one having to deal with jacks and also supporting front).

Second: the drop of eco value. The value of that is hard to measure but it can easily make jack drop cost effective. In this game team north reacted perfectly rezing singu super fast. But this is another instance where thinks can go wrong and they often do. Keep in mind in this game it was better eco that allow north to stay even on battlefield with their attrition being worst.

Third: the counter measure. This is real reason why team north lost. They build 40 picets, 20 gnats, 8 locust and 9 harpy that just protected back singus for rest of game (total of 10 000m (!)). To be fair it destroyed that single jack at 33:43 before he ever landed. In that time team south build zenith and won game after. Now after match we can easily point that as mistake, but u never know if and when drops will continue.
In my opinion this is the biggest reason why jack ramp is hard to deal with optimally. U can drop single jack or dozens of pyros and jacks in a steam. U can also choose a time of that. So as defender what do u do? Sent units on patrol or build defense to have your full apm on front lines? That is metal wasted in back of your base. Also how many units should it be? 10 000m worth of value is surely enough and it would make cost against that Jiggles guy, but not against someone that know when to stop. Do u split your apm between front and back? That increase risk of mistakes. And in game so chaotic as big lop pot that risk is high. I never saw anyone make chat announcement: "Don't worry guys i will deal with jacks u do your job and don't get distracted, meanwhile u XXX take my units and command them for now".

So yea i believe a good used jack drop can change (or at least affect) front situation, and decide game outcome because of long term damage to economy or misused metal.
It affect game in bad way - exploiting lack of good communication that is THE best way to counter jack drops (in this game 2 ppl spend metal to deal with potential jacks that never really came - 1 building picets, 1 gunships).

And pls don't say team north would lost regardless cause they never consider starting a super despite having eco advantage. I think point still stands