If they continue to lose, there will be no change at all, even if they change their playing style. To be honest, we don't know whether Manchester United is improving or Arsenal is declining in yesterday's match, we simply don't know.
And it’s true that this is just the start of the season, so we don’t know how it will turn out. A team’s performance can change at any point during the season, either improving or worsening, depending on how they adapt and progress in securing victories in each match. Underestimating them at the start of the season is overly excessive, except for those who are disappointed.
I also think is very difficult to predict what will occur at beginning of new season. It is too early to draw any conclusions since initial matches of team do not always reflect on how team will finish up. It is factual that we can not be too sure whether Manchester United is improving or whether Arsenal is just on temporary downfall. Both teams are yet to be in their stride. It is wise to be cautious when it comes to determination of fate of team so early. Key factors to successful season are to play consistently and learn to change and get better. Teams, who learn their mistakes, will be ones that do well in end.