The Cost of Centralization in MEV-Boost Relay Networks

Relays are the final arbiters of which blocks reach validators. A dominant relay can enforce OFAC compliance, creating systemic transaction censorship risk. This violates Ethereum's credibly neutral base layer promise.

• Single Point of Failure: Top 3 relays control >90% of post-merge blocks.
• Regulatory Capture: Compliance becomes a centralized policy decision, not a protocol rule.

If a major relay goes offline or is attacked, a significant portion of Ethereum's block production halts. Validators are dependent on relay uptime, creating a liveness vulnerability absent in the base protocol.

• Infrastructure Risk: Centralized operational security and DDoS surfaces.
• Validator Lock-in: Switching relays mid-duty is non-trivial, creating sticky centralization.

Relays operate as opaque profit centers. They capture value through priority fees and MEV sharing, but their fee structures and builder selection logic lack transparency and are not credibly neutral.

• Opaque Auctions: Builder selection and payment flows are not verifiable on-chain.
• Value Extraction: Creates a rent-seeking layer between searchers and validators.

The only durable solution is to enshrine Proposer-Builder Separation (PBS) and relay functionality directly into the protocol consensus layer. This eliminates trusted intermediaries and makes the block market credibly neutral and Byzantine fault tolerant.

• Protocol-Level Trust: Relays become a permissionless, slashed role.
• Eliminates Chokepoint: Block censorship requires attacking the consensus layer itself.

As a transitional architecture, SUAVE (Single Unifying Auction for Value Expression) aims to decentralize the pre-confirmation space. It creates a shared, neutral mempool and execution environment for cross-domain MEV, reducing reliance on centralized relay order flows.

• Unified Liquidity: Breaks down domain-specific MEV silos.
• Intents Standard: Moves towards a user-driven, competition-based flow.

Validators are economically incentivized to use the most profitable relay, creating a coordination tragedy. Even if decentralization is preferred, individual rational actors converge on centralized options, cementing the trilemma.

• Principal-Agent Problem: Validator profit ≠ network health.
• Coordination Failure: Requires social consensus or punitive slashing to correct.

Relays act as gatekeepers, enabling OFAC compliance that censors transactions. This violates credible neutrality and creates legal liability for validators.

• Top 3 relays control ~90% of relayed blocks.
• >50% of post-Merge blocks have been built under OFAC-compliant rules.
• Creates a single point of failure for network-level transaction inclusion.

Relays are opaque profit-maximizers. Validators cannot audit the fairness of payment splits or verify if they receive optimal MEV.

• Sealed-bid auctions hide true bid values from validators.
• Creates principal-agent problem: relay's profit incentive ≠ validator's.
• Enables stealth margins where relays capture value between searcher bids and validator payments.

Centralized relay infrastructure is a critical liveness risk. An outage at a major relay can stall block production for a significant portion of the network.

• Flashbots Relay outage in 2023 caused a measurable drop in proposed blocks.
• Creates re-org risk if relays experience synchronized failures.
• Contradicts Ethereum's design goal of client and infrastructure diversity.

Relays have outsized influence over MEV-Boost's development and roadmap, creating a path dependency that stifles innovation like PBS, SUAVE, or mev-commit.

• Centralized roadmaps prioritize relay profitability over protocol health.
• Creates a moat that disincentivizes the adoption of decentralized alternatives.
• Slows the transition to in-protocol solutions outlined in Ethereum's endgame.

A handful of relay operators control block inclusion, creating a single point of failure for OFAC compliance and arbitrary transaction filtering. This undermines credible neutrality and network liveness.

• Risk: ~90% of post-merge blocks are built by relays subject to OFAC sanctions lists.
• Consequence: Creates legal and reputational risk for protocols that require uncensorable execution.

Centralized relays act as rent-seeking intermediaries, capturing value that should flow to validators and users. Their opaque operations hide the true cost of MEV extraction.

• Cost: Relays capture a significant portion of the $1B+ annual MEV market as an implicit tax.
• Inefficiency: Creates misaligned incentives, discouraging competition and innovation in block building.

The endgame is enshrined Proposer-Builder Separation (PBS) and chains like SUAVE that decentralize the relay function. This moves trust from entities to cryptoeconomic security.

• SUAVE: Aims to be a decentralized mempool and block builder marketplace.
• Enshrined PBS: Bakes auction mechanics into the protocol consensus layer, eliminating trusted relays.