Mattgrey,
The Stuka was, as you say,successful against shipping. The RN losses that you quote during the campaign on Crete were very significant. But, the statement 'bereft of air cover' is also relavant. With little RAF air cover over Crete, the Luftwaffe had the advantage. With fighter cover, the RN losses in Crete would have been less and the Stuka losses would have been higher. One only has to look at the Stuka losses over the UK to realise that. No doubt a versatile aircraft (Tank Buster etc,) and I was surprised to see how big it was when I saw one in real life.
Temps