The match against Southampton at the weekend should be an easy match for Manchester United, considering that Southampton is currently in a bad condition after consecutive defeats, but we also cannot guarantee that Manchester United will win easily in this match, because the strategy often implemented by Ten Hag in a match actually became a Boomerang which destroyed themselves like when they faced Brighton in previously match.
The first three lines of your post was beginning to make me doubt your football knowledge but when I read to the last three, I came to realize you're very much aware of how unpredictable Manchester United is since Erik ten Hag became the manager of the English Premier League club. Southampton will play that game against Manchester United at the Saint Mary's stadium which is their home and fortress so I expect them to put in their best in that game in other to get a good result.
That being said, Manchester United like I earlier said is very unpredictable which is why I can't totally write them off in getting all three points from that game. If the Red Devils can be at their best with the quality and world class players at their disposal, I think they can as well have an easy day at the office in that game