He hasn't thought mate, and that's the worry.
Even against Sunderland where we were abysmal, Lukaku barely tried- but at least he could control the ball, get into the right areas, generally understand the flow of the game. He just wasn't fit enough, nor bothered to influence the game.
You watch Naisse vs Leicester or Bournemouth and it was as if he'd been introduced to a mysterious new game for the first time. He's being laughed at by the youth teams when they do combined sessions - and if you watch the pre-match and half time warm ups players like Mirallas pass the ball fast at him and laugh (did this in front of the away fans halftime vs Palace)! It's all a bit grim