Polygon Validator Effectiveness Rating
Methodology that underlies the effectiveness rating of validator and operator performance on Polygon.
This effectiveness rating is a measure of how well a validator has been performing its rewarded duties over time.
It seeks to be a true measure of performance, attributing points to the validator for attributes of their onchain footprint that they have influence over (e.g. whether they are signing checkpoints, which implies that they are default online), while dampening the effect of metrics that allow randomness to creep into the measurement (e.g. signing performance of other validators).
The Polygon Effectiveness Rating is designed to work with the validator ID as the base unit of account. What the metric effectively does is to tally up the duties that a validator ID is called to perform over a given time period (e.g. 10 checkpoints, a day, a year), and assign points to those instances when duties were completed successfully. The result is a percentage score that illustrates the job completion rate of a given validator ID.
Applicable to October 13, 2023 onwards (Heimdall Checkpoint Number 52108)
Components of Effectiveness
Checkpoint Proposer Effectiveness
Checkpoint Signer Effectiveness
Bor Proposer Effectiveness
In the following sections, we examine those one-by-one and then synthesize them together in what constitutes the effectiveness rating.
Checkpoint Proposer Effectiveness
True finality of Polygon’s transactions are dependent on its state being posted on Ethereum. Given this, validators are assigned to propose the checkpoint transactions on a separate chain called Heimdall, wherein these checkpoints contain the state of a set of Bor blocks. As such, the formula for this is the following:
Where checkpoint proposal duties are the total number of times a validator had a chance to propose a checkpoint. The reward for this is 10% of the protocol’s emissions per checkpoint. The protocol’s emissions per checkpoint is actually dependent on the number of Bor blocks contained in the checkpoints. There is a protocol limit of 5,120 Bor blocks per checkpoint. If a proposer includes this many blocks in their checkpoint, full emissions are released (71,795 MATIC). Rewards are modulated based on how many blocks are actually checkpointed, as in:
A proposer can wait for more Bor blocks to come in before proposing a checkpoint to maximize rewards but that comes at a cost of time to finality (i.e. waiting for more blocks to checkpoint means delaying the checkpoint itself), which is not ideal from the protocol’s standpoint. This seeming contradiction between validator rewards and protocol finality is the main reason why we did not include any checkpointed blocks modulation in the checkpoint proposer effectiveness measure. We would like to open the floor for the community to chime in and let us know their thoughts on how to best strike a balance between these two.
If you would like to share your thoughts on the matter, head on over to our forum at https://rated.discourse.group/.
Checkpoint Signer Effectiveness
Validators on Polygon are expected to sign every checkpoint that gets proposed on the Heimdall chain. As such, the simple formula here is the following:
Where checkpoint signing duties are the number of checkpoints in a given period of time. Checkpoint signers share amongst themselves 90% of the protocol’s emissions per checkpoint. We further go into these rewards in our validator and delegator APR sections.
Bor Proposer Effectiveness
Finally, validators are expected to propose blocks filled with end-user transactions on the Bor chain. Bor is where transactions on Polygon happen. Validators build blocks containing these transactions and propose them to the network. In return, they receive rewards from priority fees and any maximum extractable value (MEV). The formula for this is the following:
Where Bor proposal duties are the number of times a validator is assigned to propose a Bor block.
Effectiveness Rating
In order to come up with a unified validator effectiveness score, we combine the checkpoint signer, checkpoint proposer, and Bor proposer effectiveness ratings in a weighted average. We attribute the following weights to each based on the distribution of rewards using the most recent data from the Polygon PoS chain:
Checkpoint Signer Effectiveness: 85%
Checkpoint Proposer Effectiveness: 7.5%
Bor Proposer Effectiveness: 7.5%
Such that the formula becomes:
If a particular validator has not been assigned a particular duty for a given time period, we only take the effectiveness of whatever duty they were assigned with and had a chance to fulfill. Example is when a validator has not been assigned a checkpoint proposal duty or a Bor block proposal duty for a given period. In this case, effectiveness == checkpoint signer effectiveness.
We remain open to inputs from the community on how to best capture the effectiveness of a validator on Polygon. Head on over to our forum at https://rated.discourse.group/ to share your thoughts.
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