Everton completely changed their style of play for him... it's why Jelavic went from fucking ace to seemingly crap overnight. He needed the ball playing in diagonally in front of him on the deck.
Lukaku needs crosses, which they duly started supplying. So the answer is, no, we should have signed Jelavic.
Don't take my word for it though...
http://bleacherreport.com/articles/...-evertons-nikica-jelavic-and-his-loss-of-form
EDIT: They didn't change it for him, they changed it for Fellaini first. Whatevers. There was some other article showing that if you slid the ball in front of Jelavic 20 yards out he scored 2 in 3. That seems to be more the kind of player we need than a big fucker who gets on the end of crosses.