I am afraid I cannot give you advice on tactics. With available information, I think your tactic on 1st match is adequate. No comment for 2nd match because there's no information.

After almost half a season, the past results can fairly reflect the competitiveness of teams. If your opponent strongly performs in league, you must regard it as a strong team even if their average or starter quality is not high. Teams can be strong because of different factors. We may not fully understand through information available through T11.

I also want to remind you that player form is important. If some of your players poorly perform, you may need to bench them for a while. The highest quality player player is not necessarily the player who can contribute the most in all matches.

The most dangerous player of opponents may not be the highest quality player. For example, wingers are usually most dangerous players, my highest rating players and best scorers of my teams. However, their qualities are usually obviously lower than team average because I seldom replace(upgrade) them.

In my opinion, the quality difference between your team and your opponents are not large enough to guarantee your team for victory. If opponent have good past record, I must respect them and be more careful. If a very dangerous player of opponent is identified. I may try to limit his activities e.g. putting more players around him.

In conclusion, if your team performs more poorly than you expect, I suggest to firstly 'manage' player form. Identifying your poorly performing player is first step. You may place them in bench or even replace them with new player even if their quality is high. If some players consistently performs in all matches (not necessarily the best player), I suggest to rely more on them and keep it as regular starter. In my opinion, formation should maintain some consistency in order to ensure longer success.