In InitialSyncer::_enqueueDocuments() there is a TODO (line 2256) to update metrics with OplogFetcher::DocumentsInfo. This struct carries per-batch counts for networkDocumentCount, networkDocumentBytes, toApplyDocumentCount, and toApplyDocumentBytes.

Currently there is no visibility into oplog fetch throughput during initial sync. Adding running totals for these fields to InitialSyncSummaryStats would expose them via replSetGetStatus and FTDC, enabling diagnosis of slow initial syncs where the bottleneck is in the oplog fetch/apply phase rather than data cloning.