It was nearly at this point of last season when Everton embarked on a run of just one win in 11 games while Koeman experienced a similarly lean spell with Southampton the season before.
And Jagielka admits that they have not yet found a solution to the problem of how to replace Lukaku's goals.
"The number of appearances, the number of goals, the number of trophies".
They go into the weekend top of the Premier League and have already spent more nights top of the tree this season (34 up to an including Friday night) than in the previous four seasons combined (16), since the departure of Ferguson.
Goals have also been hard to come by for Ronald Koeman's side, who have scored just twice in the league this season, with Rooney netting both - the forward is price at 12/1 (13.0) to open the scoring or 4/1 (5.0) anytime.
Rooney, who since returning to Merseyside has retired from worldwide football, is also the highest scorer in United's history and this Sunday returns to the club where he scored a record 253 goals in 559 appearances.
"If we defend like we have the last few games, maybe it's his afternoon".
Sandro Ramirez and Rooney were forwards signed by Koeman in the offseason but neither player is in the mold of Lukaku, a powerful target man who stretches defenses with his pace. We have a really busy month ahead. The team is far away from what we need to show.
He stressed that there was "no panic" but added: "It would have been nice to pick up more points".
"It's how you look at the Sunday game".
"He's come in the right moment of his career".
"Christmas is crunch time".
Manchester United have won 18 and lost just one of their last 24 Premier League home games against Everton, losing 0-1 in December 2013 while former Everton boss David Moyes was in charge of them.
"We've had some close encounters with United", he said.
"I'm not going to analyse in that perspective", Mourinho said.
"But [we'll] talk after the match when the players' dressing room and my office are open for him".