Xabi Alonso's first debut in the Champions League yielded quite satisfactory results, his team was able to score 4 goals at Feyenoord's headquarters, it was a big blow for the home club, Feyenoord had scored a goal but the goal they created was disallowed for offside so Feyenoord could do nothing but accept the defeat besides that the goalkeeper Timon Wellenreuther also made a mistake by putting the ball into his own goal which added to Leverkusen's total score I'm sure the Feyenoord players must be increasingly frustrated because they couldn't reply to the goal against Leverkusen even in the second half they couldn't do much.
I think Leverkusen will be the dark horse this season so clubs like Bayern Munich, Real Madrid and Man City have new competitors this season who also have a chance to compete for the UCL title.
Feyenoord is not a weak team so this big win is a massive win for Leverkusen. It is a big win of course, but more than that it shown very good quality of Leverkusen. It proves that their success last season is not by chance but actually comes from their hard-working and they already improved their quality and competitiveness a lot.
Leverkusen are ready to compete well in Champions League and they don't participate in Champions League this season with fear but with high confidence about their ability to beat opponents around Europe and are ready to go far.
I think this is a loss for Arsenal. If you ask why, Atalanta has been in a lower than expected performance since the beginning of the year. They played very well in the match with the weight of the Champions League and deservedly got the draw. They were unlucky because they could have won. I think this is a negative match result for Arsenal. Because Arteta believed he could win this match but the players could not show the necessary performance on the field. Still, a draw is a better result than a defeat.
At least it is a draw, not a defeat and the opponent is not weak, but strong enough. So this draw is not a loss for Arsenal even result is disappointed and not their expected result. Arsenal have many matches in group phase to fight, get good results, and move to a next phase of Champions League.
They shown that they are ready to learn and improve themselves in latest seasons and this draw will be part of hard lesson they learn, to improve themselves more. It's not the end, but beginning of a brighter chapter for Arsenal.