Jelavic opened his Everton account on his home debut against Tottenham.
Cahill said: "I remember when we finished fourth we were winning a lot of games 1-0 and it was ugly sometimes, but the main thing is making sure the discipline and attitude is there. The quality will show through.
"The effort from the team was tremendous. We try and instil that discipline, and hard work always. The gaffer has done that over 10 years here from when he first came in.
"It does make a massive difference having Nikica finishing one chance, one goal and the way he holds the ball up too."