  The MEV-Boost block auction contributes approximately 90% of all Ethereum
blocks. Between October 2023 and March 2024, only three builders produced 80%
of them, highlighting the concentration of power within the block builder
market. To foster competition and preserve Ethereum's decentralized ethos and
censorship-resistance properties, understanding the dominant players'
competitive edges is essential.
  In this paper, we identify features that play a significant role in builders'
ability to win blocks and earn profits by conducting a comprehensive empirical
analysis of MEV-Boost auctions over a six-month period. We reveal that block
market share positively correlates with order flow diversity, while
profitability correlates with access to order flow from Exclusive Providers,
such as integrated searchers and external providers with exclusivity deals.
Additionally, we show a positive correlation between market share and profit
margin among the top ten builders, with features such as exclusive signal,
non-atomic arbitrages, and Telegram bot flow strongly correlating with both
metrics. This highlights a "chicken-and-egg" problem where builders need
differentiated order flow to profit, but only receive such flow if they have a
significant market share. Overall, this work provides an in-depth analysis of
the key features driving the builder market towards centralization and offers
valuable insights for designing further iterations of Ethereum block auctions,
preserving Ethereum's censorship resistance properties.
