Mirallas put in a fine performance against United, scoring an excellent 43rd minute goal, whizzing a shot past David De Gea into the side netting at the far post, and demoralizing the Red Devils and now departed David Moyes right before the break.
Distin's season has been one that has left us wondering if the 36-year-old defender is ever going to start showing signs of aging on the pitch. He has combined well with youngster John Stones in the period since Phil Jagielka's injury.
All eyes will now turn to Jagielka, the club captain, if Distin is unable to play the rest of the season. Jagielka was rumored to be ready for a return against United last weekend, so there is hope that the Englishman can step back into the lineup starting at Southampton Saturday.
If he cannot, the duty will fall to the Paraguayan Antolin Alcaraz. Alcaraz filled in for Distin well in the second half against United, and formed a decent and at times even solid partnership with John Stones during an earlier period of the season when Jagielka and Distin were both injured.
Still, with a matchup against Manchester City looming, Evertonians will be nervously eyeing the physio's room for Jagielka, alarmed by the thought of Alcaraz and Stones facing the likes of Sergio Aguero, David Silva, and Yaya Toure, particularly given that Gareth Barry will be ineligible to play against his parent club.
Roberto Martinez will face an equally sticky situation in trying to replace Mirallas. With Steven Pienaar already out with a knee injury (and looking like his season may be done as well), options at wing are getting thin.
Martinez has started two true wingers only once in Everton's last four matches, a loss in a somewhat failed tactical experiment against Crystal Palace. Against Arsenal, Sunderland, and United, we saw Lukaku, Osman, and Barkley line up at wing respectively.
It is very possible we will continue to see one of those players on one of the wings, but Martinez will surely want at least one true winger on the pitch, which means supporters will be seeing one or both of Aiden McGeady and Gerard Deulofeu playing a massive role for the rest of the season.
Deulofeu, as our writers and readers alike have both noted, is simply bursting with talent, but has a lot of learning to do in terms of his decision making. He can take on defenders like no other Toffee can, but often gets caught in possession, trying to do too much.
McGeady, brought in during the January transfer window, has shown flashes of what Martinez was surely looking for when he was brought in, but still, understandably, is adjusting to the English game and returning to form after a long spell off the pitch in Russia. Martinez certainly would have preferred to wait until next season to thrust the Irishman into a role such as the one vacated by Mirallas, but he may have little choice now.
Additionally, a midfield player may very well have to step up in the goal scoring department to compensate for the loss of Mirallas. The Belgian has nine goals this season, three of which have come in his last four matches. Ross Barkley, Leon Osman, Deulofeu, or McGeady may have to find the net a few times in the Toffees' last three matches if they are to take the nine out of nine points likely needed to qualify for the Champions League.
In the end, we will learn a great deal about Everton's Champions League credentials in the next three weeks. If the Toffees can win their remaining games with Mirallas and Distin out, they will have shown that they have the squad depth needed to be a Champions League club, and hopefully will get the modicum of help they need to get there.
If they cannot get the job done without these players, then perhaps Everton isn't quite at the Champions League level yet.