I cannot agree that Manchester United has no problems in attack. Because in the last few matches, I have seen Manchester United's weak attack. Manchester United have scored just 3 goals and conceded 7 goals in their last 5 matches. So Manchester United's defensive performance as well as their attacking performance is very weak now. And so if Manchester United want to qualify for the Champions League, and stay in the top four of the points table, they need to improve both defensively and in attack.
I agree with you too. Manchester United have problems in both attacking and defense but more problems in defense than in attacking areas. Their midfield area was improve by Casemiro but in next one to two seasons, they will need to find other younger midfielders to support then replace Casemiro.
Their attacking system looks to be not troubling in this season with suddenly good performance from Rashford but we see how they struggled to have goals after Rashford starting to have worse performance. They can not rely on a single attacking player like Rashford and other players like Sancho, Martial, Werghost are not good enough for them.
These days, Arsenal games look fantastic. This is what they should have done from the start to prevent Manchester City from overtaking them as league champions, but they still have a chance to do so because Manchester City is only one point ahead of them. I know how strong Manchester City is as a team, but if Arsenal played well and scored more goals than Manchester City or Manchester city lose some matches, it would help them regain their lead.
Beating Newcastle United impressively is important for Arsenal. It confirms their quality and strength and it is a confirmation for their growth in the latest two seasons. It is also a good continuation for them in a next season. Even if they fail in the race with Manchester City, they know that how strong and competitive they are.
Speaking of Liverpool, I think the remaining games against the other teams won't be too challenging for them, and since Manchester United isn't treating their games seriously right now, Liverpool will assume the lead because they're willing to do so and miss out on the champions league next season.
Liverpool just woke up too late and they now only can try their best and hope that Manchester United will have very poor performance in remaining matches. If they had woken up earlier, they would have gotten a bigger chance to end in top four.