Aaron Wan-Bissaka has been a “big plus” for Manchester United, says Denis Irwin, with the 21-year-old boasting the potential to help get the Red Devils back in the habit of collecting clean sheets.Only one shut out has been secured by Ole Gunnar Solskjaer’s side in the Premier League this season, with that coming on the opening weekend in a 4-0 victory over Chelsea.United have not looked watertight since then, with questions once again being asked of a back line that includes David de Gea – one of the best goalkeepers in the world – and £80 million man Harry Maguire. Article continues below Editors’ Picks What is Manchester United’s ownership situation and how would Kevin Glazer’s sale of shares affect the club? Ox-rated! Dream night in Genk for Liverpool ace after injury nightmare Messi a man for all Champions League seasons – but will this really be Barcelona’s? Are Chelsea this season’s Ajax? Super-subs Batshuayi & Pulisic show Blues can dare to dream Wan-Bissaka has looked impressive on the right of the back four and is considered to have been one of few bright spots for the Red Devils so far in 2019-20.United legend Irwin, himself a full-back of the highest order, hopes there is even more to come from the youngster, with those at Old Trafford needing inspiration across the field.“I saw him play for [Crystal] Palace quite a bit last year, and he only played for the Palace first team for 15 months,” Irwin told United’s official website.“He spent [his younger] years as a right winger, so what surprises me is how good he is defensively. Not just the tackling, because we saw that last year and in the first four games of this season, but the positions he takes up are very good.“You always worry about a winger when they transform into a full-back, it can take them a while to get used to that. He seems really good at that. Obviously he’s a young lad and has a lot to learn yet, but he’s been a real plus.“Last year we conceded 54 goals in 38 games. That’s not really Manchester United, we’ve always been good defensively. We need to strengthen, which we have done, and we need to keep more clean sheets.”Wan-Bissaka is not the only 21-year-old new arrival to have outperformed a number of more senior and experienced stars at United this season.Daniel James has also caught the eye since arriving from Swansea, with the jet-heeled winger having found the target three times in his four outings to date.Irwin said of the Wales international: “He’s a player that can play on both wings and can cut in on his left and right.“I think we’ve seen that already.“He’s not afraid to run at players with his pace and you always want players like that to chip in with goals, but to score three in four is a really great start for him. Some of the balls he puts in, particularly in the latter stages against Southampton last Saturday, were a joy to watch. He’s been brilliant.” Check out Goal’s Premier League 2019-20 fantasy football podcast for game tips, debate and rivalries.