The Belgium international is enjoying his best individual campaign of his career, scoring 18 goals and adding a further six assists in 33 Premier League matches thus far.
However, since scoring both goals during the Toffees’ 2-0 FA Cup quarter-final win over Chelsea, Lukaku has failed to net in his last while his overall performance levels have suddenly dipped.
Commenting for BBC Radio Five Live, Kilbane was critical of the striker and expected more from him.
"Romelu Lukaku has not been at it since that night at Goodison Park (FA Cup quarter-final). He is not working as hard, not holding the ball up as well,” Kilbane explained.
Nobody could question Lukaku’s effort at Wembley on Saturday, however his disappointing run in front of goal continued as he missed a host of chances as his side succumbed to a 2-1 defeat.
The 22-year-old had two superb opportunities to give Everton the lead in the first half, while he saw a powerful second-half penalty saved by Manchester United hero David de Gea.
Roberto Martinez’s side gave a good account of themselves, yet they will only have themselves to blame when looking back on defeat with Tom Cleverley and Lukaku so wasteful in front of goal.
Everton’s record signing has already spoken of his desire to play in the Champions League, yet on recent showings he may struggle to find a suitor willing to pay the club’s likely extravagant asking price.