The Duke of Parma wasn't a Admiral.
It would have been better if the plan of attacking Ireland from Spain had been performed in combination with a later attack by Parma from Flanders.
If the Spanish fleet had attacked Ireland landing a decent army there the English fleet would have had to go to Ireland leaving small forces in the channel that could not have been able to stop the invading fleet. Of course the problem were the small dutch ships patroling in the coast...It could work I imagine, although might not the English navy have a decent chance against a small one coming from Flanders.
Of course right now it sounds very smart to take Ireland, but Philip II is not very likely to understand why it's a good idea. He just wants to liberate England from it's heretic queen.
But the POD could be, what if Philip II was the most clever strategist of his time or, WI Philip II had the greatest strategist of his time in his service and was willing to listen to him.
If we somehow end up with independent Ireland and catholic England it would be cool.
Everytime some a succesful armada comes up, I always wonder about the situation in the Netherlands. With the army of Flanders in England (or Ireland) doesn't that mean that the Spanish lose most if not all the Netherlands. And with the army overseas and a hostile English and Dutch fleet, doesn't that basicly mean that they are trapped in England without reinforcements or supplies?
But, if the Armada is succesful, and being Mary Queen of Scots dead, who would be the English monarch? Or Philip II would claim the throne for himself?
It would not have been easy to cross, but with an invassion in Ireland going on not so many ships would have been around the Channel and Parma would have had an opportunity of crossing without many loses. How long would it take to cross? The problem would have been the dutch ships.
As for the situation in Flanders, the United Provinces were considering giving up. They were at their lowest and the english help was anything but helpful (in fact english commanders were very fond of changing sides for a price in gold), and the invassion of England would have seen by then as a tremendous blow on the only power that was supporting them. They would have sued for peace for sure.