I just want to point out that the shriekers in the rush I use are minimal. Two. In fact, replacing them with antlions might be better.
I also don't agree with graboids being overpowered. Take a giant frog. 5/3 for 2 life. A graboid (shrieker) is 10/4 for 3 earth and 1 time. Overall it's the same cost/damage ratio with graboid just having double the strength and double the cost. Keep in mind, however, that graboid only does two damage the first turn it's out and in some ways that's a negative since then the opponent has a turn to prepare for the shrieker. They come out slower compared to giant frogs.
After two turns, a graboid will have done 12 damage for 3 earth + 1 time, while a giant frog will have done almost the same (10 damage) for a simple 2 life. Granted, from there, graboid takes the lead, but until that point it's worse. Also of note is that if you extrapolated a giant frog to 10/4 and doubled the cost to 4 life, that 4 life would be MUCH easier to pay for rather than 3 earth + 1 time. Needing time mark hinders the deck, especially in the face of devourers, black holes, etc. Saying graboid is overpowered and giant frog is not is like saying a 1/1 creature for one quanta isn't overpowered but a 2/2 for two is (though the 2/2 is stronger in some respects, it's worse in others).
Also, shriekers aren't exactly hard to deal with. Antimatter, shockwave, rage elixir, unstable gas + snipe, lightning, 10+ fire quanta fire bolt, 10+ water quanta ice bolt, 10+ dark quanta siphon life, and congeal all deal with them adequately. Reverse time also hinders the shrieker because then you have to replay it for 8, and 10/4 for 8 earth isn't that strong. And that's not even talking about all the ways to deal with them that don't necessarily deal with giant frogs. Discord, pests, black holes, quicksands, and antimatter (to a point) all hurt shrieker rushes more than giant frogs. Finally, yes, they do have burrow, but if you're forced to use it you have other problems. Namely getting beat.
Now, you may say that giant frogs are overpowered too so just because they're just as good as graboids doesn't mean graboids aren't overpowered. But I really can't see them as that overpowered. Have you seen ferox lately? Do his giant frogs scare you? No.
The only reason people see graboids as overpowered is because they turn into big creatures that their deck just doesn't counter. A deck that losses to graboid/shrieker rushes would probably lose to a mono life rush or an immolation deck just as much. At the same time, they have a multitude of counters, which is why they aren't run very often in championship league matches anymore. Decks with lots of antimatters, speed rainbows, immolation decks, fire stalls (especially), aether/earth or mono aether, decks with pests, decks with black holes, decks with discord, decks with an abundance of shockwaves/eagle eyes/unstable gasses, and more all counter them. Do we need to nerf all of those decks too?