"He's an Everton man", "He loves and understands the club", "He's done great things with the Academy sides", etc. are not any form of indicators of an ability to manage and coach a PL team in turmoil and Everton are in turmoil.
Given a general lack of pace at the club, Unsworth selected Mirallas and Lennon up front. Unfortunately, Wayne 'Pirlo' Rooney decided not to play close to centre forward Calvert-Lewin, as he was picked to do, but drop deep into midfield where he has zero effect. The lack of pace in a back 4 up against Vardy should be a distinct worry but instead of staying compact, Everton played wide open in the first half and let Leicester run them ragged. At 2-0 it's game over at half time, Everton aren't scoring 2, let alone 3.
There's a dangerous mix of slow older players, inexperienced young players being excessively relied upon and a severely out of sorts midfield. With Siggy, Gueye, McCarthy and Schneiderlin and young Davies, they should be able to muster something relatively decent but it's a shambles. Someone needs to get in there and stop the goals going in because it's unlikely that they'll outscore anyone. Where's Sam?