Firstly, yes your team has a higher average quality than his, but in the scheme of things it's not much. Especially since in level 1 differences in quality don't count for much.
Secondly - I play 4-4-2 classic a lot. I tend to play it when i come up against a team that also plays it. Those are always tough matches. There was no way you were going to win 4-0 in that match with those formations.
Thirdly - You say their defence stopped 15 goals - that's not the case. The stats there show the number of shots you had. The one below shows the number that were on target. so they stopped 5 shots, and probably stopped you a lot more before you had a shot.
Fourthly - You will learn that possession doesn't mean that much in this game.
Finally - You don't know what his tactics were - for example if his were set up as defensive mentality with hard tackling and force counter attack, and yours were attacking, then the result is not that surprising. Also, like in real life, flukes will occur.