Why MEV Relays Are Centralizing Forces in Disguise

Relays are centralized gatekeepers. They are the sole arbiters of which block builders can access proposers on networks like Ethereum, creating a permissioned entry point for the most valuable resource: block space.

Economic incentives drive consolidation. The winner-take-most auction model for block space favors large, sophisticated builders like Flashbots and bloXroute, which can afford to pay the highest premiums to relays.

This creates systemic risk. A relay outage or malicious action can halt chain finality, as seen in past incidents with the Flashbots relay, demonstrating the fragility of this centralized abstraction layer.

Evidence: The top three Ethereum relays consistently control over 90% of relayed blocks, creating a de facto oligopoly that dictates the rules of MEV extraction.

Relays are natural monopolies. They compete on speed and reliability, which favors massive, low-latency infrastructure. This creates a winner-take-most market where a few dominant players like Flashbots and bloXroute control the majority of block flow.

Relays centralize validator choice. Validators outsource block building to the most profitable relay, creating a single point of failure. This delegated censorship allows relays, not validators, to enforce OFAC compliance, as seen with Flashbots' dominance post-Merge.

The builder market is an illusion. While builders like Titan and rsync compete, they all submit to the same few relays. The relay is the gatekeeper, determining which blocks and transactions are even considered by the network's validators.

Evidence: Post-Merge, over 90% of Ethereum blocks are built via relays, with Flashbots consistently commanding >40% market share. This concentration directly contradicts the network's distributed validator set.

Relays control block space access. They are the mandatory gateway for builders to propose blocks to validators, creating a single point of failure and control. This architecture centralizes the flow of transaction ordering.

Economic incentives favor consolidation. The largest relays like Flashbots Protect and bloXroute attract the most builders, creating a feedback loop where liquidity and order flow centralize to maximize extractable value.

Censorship is a protocol feature. Relays like Titan Builder and Manifold can and do filter transactions based on OFAC lists, making censorship a service-level decision rather than a network-level consensus failure.

Evidence: Post-Merge, over 90% of Ethereum blocks are built by a handful of builders, all routing through the same dominant relays. This creates a permissioned layer for block production.

Relays centralize block production. Builders compete to send the most profitable blocks to a handful of dominant relays like BloXroute and Flashbots Protect. These relays become the single point of censorship and failure for the entire validator set, directly contradicting Ethereum's distributed ethos.

They create validator cartels. Major staking pools like Lido and Coinbase run their own relays, creating a closed-loop system. This vertical integration means the largest capital pools also control the critical information pipeline, disincentivizing independent validator participation.

The 'public mempool' argument is obsolete. Protocols like Flashbots' SUAVE and intents-based systems (UniswapX, CowSwap) demonstrate that private order flow and encrypted transactions are the future, making the current relay model a temporary, centralized crutch.

Evidence: Over 90% of Ethereum blocks are built via relays, with the top three controlling the majority. This concentration creates a protocol-level single point of failure that a regulatory action or technical bug could exploit.

Relays are the new gatekeepers. They are the mandatory routing layer between proposers and builders, controlling which blocks reach the chain. This creates a single point of failure and censorship.

Builder cartels dominate relay lists. The top three builders—Flashbots, bloXroute, and Titan—win over 90% of blocks on Ethereum. This concentration is a direct result of relay-to-builder integration and capital advantages.

Proposer-Builder Separation (PBS) failed. PBS intended to separate block creation from validation. In practice, vertical integration between relays and builders recreates the centralized miner cartels it was meant to dismantle.

Evidence: Flashbots' SUAVE aims to decentralize this stack, but its success is uncertain. The current reality is that censorship resistance is outsourced to a handful of trusted relay operators.