Many fans were disappointed that the 23 year old striker had been allowed to leave the club as he was seen as an exciting prospect for the future.
The lad was a boyhood fan of Rovers and knew where the net was, even though he mainly came on as a substitute.
But even so, Derbyshire had insisted that he wanted to move from Ewood Park to go and play for Olympiakos on a full time basis after his loan spell in Greece.
Alladyce said: “I thought it was a terrific piece of business from our point of view.
“But at the end of the day it was triggered by Matt Derbyshire not wanting to stay at Blackburn Rovers any more.
“He was just as determined to leave the football club as Roque was, so at the end of the day you take the money and where you can get someone who does want to play for Blackburn Rovers.”