The start of the second half of Monday's 1-1 draw against Leeds United at Hill Dickinson Stadium, David Moyes made a rather unusual change given Everton's poor first half.
Harrison Armstrong and Dwight McNeil gave way to returning players Jarrad Branthwaite and Kiernan Dewsbury-Hall, hardly a pair of like-for-like substitutions for Moyes.
Instead, the personnel change led to a rather significant system alteration from Moyes's preferred 4-2-3-1, a setup that has powered most of the manager's time at Everton since he returned just over a year ago.
Branthwaite immediately slid in at left center back flanking James Tarkowski along with Jake O'Brien at right center back. Vitalii Mykolenko and Nathan Patterson, who started as a more traditional fullbacks, became the wing backs for the side, allowing both to push further forward, albeit with limited success.
Iliman Ndiaye remained on the left, although he was cutting inside quite often, with Dewsbury-Hall operating in a central role as well. This allowed James Garner and Idrissa Gana Gueye to roam away from their locked positions in the midfield, a tactic that led to Gana's excellent move to set up Thierno Barry's second-half equalizer.
(The caveat there, of course, is that Tyler Dibling subbed before the goal, so Everton had reverted to the back four).
The question on the minds of most Evertonians has to be whether or not this system change was one of immediate necessity (as in McNeil wasn't playing well, nor was the rest of the team, so Moyes chose to make a major switch) or if the Scottish manager has a thought to make this work moving forward.
It's pretty clear that Everton nearly have the ideal personnel to make it work. Branthwaite and O'Brien can operate in a pairing, but having Tarkowski between them can help to have a stabilizing force for when either one of the two carries the ball forward.
Patterson is closer to a wing back than an out-and-out fullback, and midfielders like Garner, Gana, Armstrong, Tim Iroegbunam, and Merlin Rohl should be able to operate in a pairing because of the defensive cover provided by having three center backs behind them.
Meanwhile, Ndiaye can play all across the front line, including behind Barry as a second striker, while Dewsbury-Hall and even Charly Alcaraz can play as an attacking midfielder if called upon. Tyler Dibling could also play there, or Moyes could opt for a version of the system with Ndiaye and Dibling on the wings, both cutting inside due to the presence of the wing-backs.
The elephant in the room on this is that Mykolenko is a purely defensive-minded left back, a fact that was wildly evident with the switch on Monday. Adam Aznou, however, would be an ideal fit here, as the cover of Branthwaite next to him would let the Moroccan worry less about defensive responsibilites.
It's pretty clear that Everton can operate effectively in this scheme, given the players in the squad, and adding a modern right back would make this even more attractive.
Whether Moyes would actually make the switch isn't clear, but Monday showed that he's got it in his mind, and it would be interesting to see him make the change when the situation called for it.