Barjonas has impressed McAllister, boss Steven Gerrard and the Ibrox coaching staff sufficiently enough to be handed a new contract tying him to Gers until the summer of 2021.
McAllister explained: “When we arrived here, we looked at him and I don’t think it’s ever been in doubt he is a technical footballer who can play football.
“His ability to get around the pitch is something we questioned – we put a programme to him and he has gone away, been diligent and come back a player in a different body.
“He is unfortunate that one of the strongest parts of our squad here at Rangers is the middle of the park.
“But I think there will be moments where we might need to call upon him and we have no doubts he can compete at this level as he has given himself a better chance – he has the body to do it.
McAllister also wants to see the new contract handed to Barjonas inspire the rest of the Academy players, adding: “I think clubs like Rangers are always looking to bring in a so-called ‘one of their own.’ It is always nice to see someone who has come up through the ranks here make it to the first-team side.
“It must give a big boost to everyone in the Academy side here. We all talk about pathways – it is the buzz word – but we want Rangers players who have come right up through the ranks to get in the first-team.
“The fans need that and the fans like to see players who make that journey from eight or nine years-old right through to playing in the first team, so good on him.”