Greece had problems

 By 1940 to 1941, Greece was politically unstable while there aspects of Greek society that were degrading their ability to resist the German attack. The Greek Royal family were German. The Greek civilian government had fallen and had been replaced by a dictatorship. General Metaxis may have been more competent than the civilian government. 

Greece had this problem that there was a segment of society that seems to have been infected with bad ideas as well as what seems like corruption. This caused problems with armies either disintegrating or surrendering. These problems were happening in April 1941 and later. 

General Metaxis was in poor health, so when he died, they were left to cobble together a new government. You had the British theater commander, General Wavell, as well as Churchill's appointee, General Wilson. It seems that Wavell was a much better commander than Wilson. 

You also had British political instability, at least iin Australia, where Churchill's misadventures in 1940 and 1941 brought down governments in Australia, where they ended up with a Labour government, although as good a one as you could hope for.

You had been through the fall of  France and Dunkirk in 1941. They eventually removed General Dill as CIGS. Alan Brooke eventually became CIGS. He eventually saw his role as keeping Churchill from causing trouble.