"The goals he got at Newcastle will have given him a huge boost to his confidence, and that win will have done the same for the rest of the Hull side" said Allardyce.
"King has the experience from being at Watford and up until he got injured he was the player they relied on.
"Perhaps him getting injured was the main reason they were unable to hold onto a place in the Premier League.
"When he returned to action with them he started scoring goals again in the Championship, and Steve Bruce saw enough in him to take him to Wigan.
"Obviously, his chances were going to be limited there and the move to Hull has been good for him."
Allardyce believes Hull will need their new players to steer clear of injuries if they are to continue their impressive start.
"When they didn't play against Wigan, Hull lost 5-0.
"They are key players as they have the experience of playing in the Premier League and they can have a big influence on other players in the squad.
"Many of the players who haven't played Premier League football before can suffer from some fear and trepidation, or perhaps it can be that they get over excited.
"The more experienced players can help keep these players focused on the task in hand."