Based on the last 5 games I would say that your team plays well. Every team has some very good players and some mediocre players. I never had a team where all players shined. Sometimes a fast trainer is right of the bat the best player in the field. I had a fast trainer who performed very poorly first season but the second season he was topscorer of my team.

Overall there is no golden rule about what team to buy to become the best. I have a team of fast trainers with SA and 6 stars or higher but I was out of the cup the first round (against the winner of the cup this season), only made it to the semi finale of the CL and I am second in the league behind a team that in Quality is about 2 points less. It is mostly random if you ask me.