Farragut's likely rank in a modern navy

Would Farragut hold admiral rank by today's standards?

Probably, because the fleet was large enough to justify admiral-level command, although a modern navy would retire him much earlier.

Farragut's command responsibilities could justify admiral rank in a modern force. The scale of his fleet and the independent operational decisions he made both support that comparison. Rank structures differ across periods, so the equivalence is functional rather than exact. A modern career system would also retire an officer much earlier instead of retaining him for Farragut's exceptional span of active service.