The Assembly Lines Era: Bundle-Boosted Beasts Changing the Game Via Private Tunnels
From open brawls to silent ambushes—MEV bots found new weapons in the dark.
The first part of this series has reviewed the prehistoric age of Sandwich MEV.
Now let’s move on to the industrial age.
Tunnels Under the Jungle
By mid-2020, a tidal wave called DeFi Summer crashed across the landscape. Decentralised‑exchange (DEX) volume had jumped twenty‑fold. Millions of dollars pulsed through mempools every hour. Slippage limits flashed like neon signs.
For sandwich bots, it was a dream come true, entering a period of MEV gold rush Ethereum had ever seen. Gas wars became daily bloodsport. The pressure was mounting on Ethereum’s block producing model.
Beneath the surface, Ethereum’s long-term roadmap was starting to bite. Two proposals loomed:
EIP‑1559 would start burning part of every gas fee, cutting miner rewards and smoothing fee predictability.
Proof‑of‑Stake would eventually replace Proof‑of‑Work mining entirely, reshaping Ethereum’s security and block production.
Both moves pointed to thinner block rewards. Some mining pools began hunting for replacement income—and they didn’t bother to hide it.
One top pool posted a blunt announcement: we will sandwich user trades and share the profits with pool stakers. The message landed badly; traders called it extortion, researchers called it a security risk. And someone decided to teach the pool a lesson.
A lone bot submitted a honeypot swap that looked like free money to the pool’s new strategy. The pool’s nodes dutifully front‑ran the bait—and lost ETH instead of earning it. Overnight, the memo was clear: in the open mempool, bragging makes you a target.
Paradigm’s Dan Robinson published "Ethereum Is a Dark Forest." The essay compared the mempool to sci‑fi wilderness: show your coordinates and you’re instantly hunted. The phrase caught fire on Crypto Twitter. More importantly, it called for private coordination—a way to trade without broadcasting your intentions to every predator.
The promise was simple: if chaos ruled the open road, build tunnels underneath. And the predators? They adapted—fast.
Flashbots Builds the Tunnel
Enter Flashbots and its modified client, MEV‑Geth. Instead of shouting higher gas bids in public, searchers could now seal several transactions into a bundle and send it straight to cooperative miners. Miners opened sealed bids, picked the fattest tip, and published the winning bundle atomically: all trades landed at once or none did. And if a bundle lost the sealed-bid race, it stayed invisible and never hit the chain—meaning no wasted gas fees for the searcher.
Within months, over 80 % of hash‑rate was processing bundles. Competitors like Eden Network and ArcherDAO popped up, but Flashbots remained the main tunnel.
New Life‑Forms Emerge
However, private tunnels didn’t just protect honest users—they empowered smarter predators. With sealed bundles came new powers: atomic execution, invisibility, and tip‑based prioritization. Sandwich bots adapted quickly. And the strategies they evolved weren’t just upgrades—they were mutations.
Here’s how the new species looked in the wild:
The Sandwich Gets Sandwiched
In the early days of this era, not all bots adapted fast. Some continued playing the old game—broadcasting their frontruns openly in the mempool. That made them easy prey.
In one now-iconic case, a legacy bot tried to sandwich a user’s swap, submitting its front‑ and back‑runs through the public queue like it always had. But a bundle‑savvy rival was watching. Within seconds, it assembled its own private sandwich targeting the first bot’s transactions—not the user’s. It bribed the miner with a 569‑gwei tip, slipped its bundle ahead, and extracted the value for itself.
The old bot paid gas... and got nothing. The sandwich got sandwiched.
Not All Bundles Are Predatory – Meet JIT Liquidity
While many predators used bundles to sharpen their attacks, not every use case was hostile. One particularly clever—and arguably beneficial—strategy emerged: Just-In-Time (JIT) liquidity (EigenPhi has published a report, MEV’s impact on Uniswap, covering JIT).
Imagine this: a swap is about to happen, but the liquidity in the pool is thin. A JIT provider sees the swap, adds liquidity just before the trade, collects a share of the pool’s trading fees, then removes that same liquidity right after—all in a single atomic bundle.
From the outside, it may look like a sandwich. But the result is different:
The user’s slippage decreases thanks to the temporary boost in liquidity,
The JIT bot earns LP fees, and
No value is extracted from the user—only from the protocol’s fee distribution.
Even more interesting: this behavior mimics a swap, but without paying Uniswap’s native swap fee. The JIT strategy is capital-efficient, protocol-aligned, and shows that MEV isn’t always adversarial. Sometimes, it’s fee arbitrage with benefits.
One Bot, Dozens of Victims
Before bundles, sandwich attacks were typically one‑to‑one: spot a user’s swap, wrap it with two trades, make a profit. But bundle protection enabled a new trick—atomic stacking.
By grouping many swaps into a single bundle, a bot could target dozens of victims simultaneously, executing all layers in one go or not at all. The result was industrial‑scale sandwiching.
In one real‑world example, a bot launched a 37‑layer sandwich that hit 35 victims in a single block. It was soon outdone by a 54‑layer monstrosity. Each layer was calibrated with precision: how much slippage could be taken, and in which direction to attack.
The age of artisanal sandwiches was over. This was automated lunch‑meat production.
Why Bundles Changed Everything
These weren’t just clever tricks. They were evolutionary leaps—mutations made possible by the privacy and precision of bundle execution. In the old mempool jungle, every predator had to show its teeth. Every frontrun was visible, every move a gamble. But bundles changed the rules of survival itself.
First came atomicity: a guarantee that your front-run and back-run would either succeed together or not at all. No more half-baked attacks. No more wasted gas.
Then came hidden contents: The chaos of public gas wars gave way to quiet, sealed auctions—managed by relay operators who throttled spam and favored strategic bidding over raw noise. While bots could still adjust and resubmit their offers, the process became private, orderly, and largely invisible to rivals.
But bundles didn’t eliminate all risks. They merely shifted them. What’s often overlooked is how these bundles altered Ethereum’s power structure. In the PGA era, miners set the order of transactions by gas bids—chaotic, yes, but directly tethered to Ethereum’s protocol. Bundles broke that tether. With Flashbots, ordering power migrated to whoever controlled the most compelling bundle—often private actors coordinating off-chain, bidding for inclusion via out-of-band tips. It was the birth of a new off-protocol layer, one where execution priority depended not on Ethereum’s rules, but on relays, builders, and private negotiation.
And when Ethereum moved to Proof of Stake, this trend deepened. With Proposer-Builder Separation (PBS), validators outsourced block construction to professional builders entirely—externalizing ordering rights as a formalized role, not just an emergent side-market. This makes the blockspace economy more efficient—but also more hierarchical. The original dream of trustless, protocol-native fairness now runs through builder relays that can reorder, throttle, or censor with little visibility. Efficiency improved, but power consolidated.
The biggest problem of the PGA era—spam flooding the public network—was replaced by a new vulnerability: centralization inside bundle tunnels. Now, relay operators sat at critical chokepoints. They could throttle, reorder, or even censor transactions—raising fresh concerns about trust, fairness, and resilience in this newly privatized layer of the food chain.
Wrap-Up the Era
Private tunnels replaced public gas wars.
Atomic bundles turned sandwiches into industrial assembly lines.
Tip auctions rewarded clever strategy over noisy bidding.
The open jungle didn’t disappear; it simply moved behind a curtain. And in the shadows of this new architecture, a darker class of predators was learning new tricks.
Coming Up Next: The Biodiversity Boom
Private tunnels didn’t tame the jungle—they fertilized it.
In the next chapter, we trace the explosion of new predator species:
🦾 Bots that borrow millions without owning a dime
🎭 Tokens engineered to tax, trap, and rug
🧠 Jaredfromsubway.eth turning MEV into an assembly-line empire
From liquidity mirages to 94-layer sandwiches, MEV isn’t just evolving. It’s speciation on-chain.
Stay tuned for Part 3: Predators Evolve – The Biodiversity Boom.
The Prehistoric Age of Sandwich MEV Before the Bundle: When Gas Auctions Ruled the Chain
In the hidden lanes of Ethereum’s blockspace, a new kind of creature has evolved—stealthy, adaptive, and precision-engineered for profit. These aren’t just bots. They are financial predators with a genetic lineage shaped by protocol quirks, mempool mechanics, and incentive asymmetries.
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