Why naval strength alone could not retain Crete

Could the Allies realistically have retained Crete?

Better command ashore was essential; naval action could help, but it could not by itself overcome the breakdown in the land defence and German air power.

The decisive weakness at Crete was a breakdown in command ashore, much like the failure at Singapore in this comparison. The Royal Navy already committed substantial strength and paid heavily while trying to support the defence. Formidable also attacked German air bases in an effort to reduce the pressure. More ships could not repair failures in the ground defence or remove the wider air threat by themselves, so retaining the island required better land command as well as naval action.