If you look at it overall, Tauchle's achievements and experience are not that great, so I wouldn't be surprised if he fails now.
In my observation, last season Bayern Munich appeared to secure the Bundesliga title through a stroke of luck, as you previously mentioned. The team's performance seemed to decline since then. However, I'm inclined to believe that Tuchel's management might not have adequately addressed this decline. Perhaps if Tuchel had scouted and acquired more talented players to replace the aging ones in the squad, Bayern's fortunes could have improved. Furthermore, it's possible that Tuchel's managerial approach isn't quite suitable for Bayern Munich.Even with the current roster, a capable manager should be able to steer the team towards success. Leverkusen squad is not as prestigious as Bayern, is proof that adept management can yield positive results even with lesser-quality players. Therefore, Tuchel's management style might indeed be influencing Bayern Munich's performance negatively.
Even though Arsenal didn't emerge victorious in their recent match against Porto, it doesn't imply they're neglecting their Champions League ambitions. Sometimes games unfold unexpectedly, and despite Arsenal's efforts, Porto managed to secure a win, perhaps through a stroke of luck. It's worth noting that Porto isn't a weak team; they're also performing admirably in their domestic league. Looking ahead to the second leg at the Emirates Stadium, there's optimism that Arsenal will give their all to clinch a victory and secure qualification to the next round. With confidence in Arsenal's abilities, fans eagerly anticipate a spirited performance in the upcoming match.