And he might also be part of a tactical plan which impressed all observers in midweek.
Mac Allister remains a big favourite fans of the Seagulls, the club who welcomed him back as a World Cup winner three years ago.
He has since played a huge part in helping Liverpool win only their second league title – and first in front of fans – since 1990.
But the dynamism and energy had reduced in early weeks of the season as Liverpool struggled to wins in the opening rounds, then completely lost their way.
Close-season personnel changes and the huge shock of losing team-mate Diogo Jota in tragic circumstances were factors in their run of defeats.
But they might also have been affected by the reduced contributions of Mac Allister, who is such a driving force from midfield.
Now, one of the people closest to the Liverpool No.10 has said the real Alexis is on the way back.
And he has also underlined the importance that stint with Albion still has in his career.
Liverpool meet Albion in the Premier League on Saturday.
Mac Allister’s brother Francis, a professional footballer with Instituto in Argentina, watches the Prem from afar.
He told The Argus: “The season got off to a difficult start for Alexis because he missed practically the whole pre-season.
“Now he is getting back to full physical fitness and he is playing in more comfort.”
Mac Allister played as the most advanced member of a diamond in midfield in what was seen as a tactical masterplan by Arne Slot as Liverpool beat Inter.
It made the Reds solid in the centre, although potentially exposed them out wide.
It is unclear whether Liverpool will go with the same plan against Albion.
Mac Allister touched the ball 46 times at San Siro.
In the last league game at Anfield, a 1-1 draw with Sunderland, he played deep in a 4-2-3-1 and touched the ball 72 times.
If that seems a strange stat to highlight, there is a reason for it.
Back in the 2022-23 season, in which helped Albion to sixth place, he told The Argus one thing Roberto De Zerbi asked of him.
It was late after a midweek game against Nottingham Forest early in De Zerbi’s tenure when he said: “In the first week the new team was here, Roberto's assistant coach told me, 'You have to touch the ball 100-120 times in a match'.
“I said, 'You are crazy, that is impossible' and then you can see that I do it.
"It is the way Roberto wants me to play, I am really happy because I like to be on the ball every time.”
Andrea Maldera was the assistant who delivered the message and Mac Allister retains a soft spot for the Seagulls.
Francis said: “He remembers his time at Brighton with a lot of affection and it is always special to play against them and to see their fans again.”
Liverpool’s midweek plan included Alexander Isak and Hugo Ekitike up front, more as individuals than as a strike partnership.
The pre-game talk will be on whether Mo Salah plays a part. For Albion fans, though, eyes will be on a refreshed Mac Allister.