Johnson - or Benedine Zidane as some dubbed the 24-year-old after the cameo - acquitted himself surprisingly well on that occasion, but it was always bound to be a temporary solution and within days Kalvin Phillips’s loan arrival from Manchester City was confirmed.
For Sunday’s 3-0 defeat by Manchester United at Old Trafford, though, Johnson’s versatility was called upon once more, the defender this time being given the nod to start the game on the right of a front three.
Again, the academy graduate, now being employed like an intern on desk rotation, did a fair job in the circumstances, but again, his novel use highlighted a glaring hole in David Moyes’s squad. Unlike in the aftermath of the Sheffield United draw, with the transfer window closed, there is no obvious way to plug it.
The deadline day (or rather, day after deadline day) departures of Said Benrahma and Pablo Fornals made sense in isolation, West Ham managing to recoup a couple of decent fees for players out of form and favour.
The failure to bring in any sort of replacement, however, is in danger of haunting the Hammers for at least as long as Lucas Paqueta remains sidelined by what Moyes revealed this week is a complicated injury, with no date yet put on his likely return.
With Benrahma and Fornals gone, the only natural wide player among Moyes’s substitutes at Old Trafford was Maxwel Cornet, and considering Johnson was preferred from the outset it seems fair to conclude that the Ivorian in not considered up to filling the void.
"With the transfer window closed, there is no obvious way to plug a glaring hole in West Ham's squad"
For 45 minutes, this was a much-improved performance from Moyes’s side in comparison to the 1-1 draw with Bournemouth on Thursday, with the Scot quickly abandoning the narrow 4-4-2 he had trialled in that tepid contest as a possible workaround to his shortage out wide.
The visitors were, however, unable to take advantage of a strong first-half showing in which they managed 13 shots but forged their only clear-cut chances from set-plays, dearly missing Paqueta’s guile.
Having probably felt hard done by to trail to Rasmus Hojlund’s fine strike at the break, the Irons were undone again immediately after it, Emerson blowing a glorious opportunity at one end before it was punished within seconds by Alejandro Garnacho’s defected shot at the other.
With so few attacking options among his substitutes, the game, for Moyes, was as good as up from that moment and Garnacho added a third to confirm as much late on.
The Hammers looked at a number of options last month, varying from Premier League experience in Steven Bergwijn, to Championship potential in Jack Clarke and the wildcard Ibrahim Osman, of Danish side FC Norsjaelland, without success.
"We’ve looked really, really hard to try and find one,” Moyes said of the club’s winger search. “We’ve made offers for some younger ones, we’ve tried for some other ones and looked really hard. We wanted something else.
“The problem you’ve got is that when you’ve got Paqueta, [Mohammed] Kudus and [Jarrod] Bowen it’s very difficult to say we’ll get one better than them.”
Which is, of course, true. But game as Johnson is, the idea that a full-back who, until a month ago, was struggling for playing time even in his actual position, is as close as you can get seems a stretch.