Most validators proposing a block right now will earn about 0.011 ETH. That's the median. But the mean is 0.050 ETH — more than 4× higher. The reason the mean is so detached from the median tells you everything about how staking rewards actually work.
Over the 30 days ending February 26, 2026, there were 200,963 MEV-Boost blocks on mainnet. I deduped them by taking the highest bid per slot across all relays. Here's what I found.
Block builder win rate is the number everyone tracks. Builder X won 18% of blocks last week. Builder Y's market share is up. But win rate hides something: most of those blocks are worth almost nothing. The real competition isn't for volume. It's for the blocks worth 0.05, 0.2, even 1 ETH in builder payments — the slots that account for a disproportionate share of all MEV value.
Looking at seven days of mainnet MEV-Boost data (~45,000 deduplicated slots), two completely different builder ecosystems are visible.
The MEV relay system starts building blocks for a slot before that slot exists. Builders are running their engines eight seconds ahead of the clock, constantly revising bids as new transactions hit the mempool. What nobody seems to have charted is what happens at exactly two seconds before a slot starts: the entire auction collapses to near-zero and then rebuilds from scratch.
Every proposer using MEV-Boost faces the same tradeoff: wait longer to capture more value, but at some point your block arrives too late for attesters to see it before they commit their vote. The timing game is well-understood in theory. What hasn't been measured is exactly where the cliff is — and how steep the drop really is.
The cliff is at 3.0 seconds. What happens after it is sharper than you'd expect.
There's a 3-second cliff in Ethereum's attestation system. Blocks that arrive after it — when validators have already started forming their head votes — cause measurable drops in head accuracy. The earlier post established that with 50,000 slots of data.
What it didn't answer: who's responsible?
I started this looking for evidence that high-MEV blocks are harder for execution clients to process. The intuition is obvious: MEV blocks are full of complex DeFi interactions, sandwich attacks, arbitrage — all the state-thrashing stuff. Surely they're heavier to execute.
They're not. The correlation between MEV block value and newPayload execution time is r = −0.004. Essentially random noise.
What actually predicts execution latency is simpler and more boring: how much gas the block used.
I found a smoking gun in the mempool data: an MEV extraction bot is being systematically excluded from Ethereum blocks with a 91.9% exclusion rate. The kicker? Higher gas prices correlate with higher exclusion rates — the exact opposite of how a functioning market should work.
The Gas Price Paradox: For one sender, excluded transactions offered 11.78 gwei on average. The single transaction that got through? 1.7 gwei. This is reverse price discrimination — the more you pay, the less likely you are to be included.