Their defeat against PSG has left many doubting Xabi Alonso's abilities, and they're also unaware that PSG themselves suffered a similar fate at the hands of Chelsea. For me, this isn't a worrying thing because in football, anything can happen beyond expectations, and while it's true that Xabi Alonso hasn't fully adapted to make Real Madrid stronger than before it's not surprising.

Ancelotti has been a coach for so long and has successfully delivered titles to the teams he's managed. Comparing Xabi Alonso to him is unfair, as Xabi Alonso is just starting to build his coaching career. It will take time for him to make Real Madrid stronger and I don't think it will be achieved in a short time as many people wish.
I don't think it's fair to judge Xabi now. He certainly had a tough time after the crushing defeat to Paris Saint-Germain, but it's also important to remember that the squad isn't finalized yet, and his preparation has been relatively short.

I think it would be fairer to judge him after the season starts. Yes, I know that was an official competition, but most newly appointed coaches often fail. I've seen him with his young players, and that makes me even more curious about what he'll do with a little more preparation.

Losing to PSG doesn't mean he's a bad coach, he's still one of the best coach currently and the team would bounce back from that defeat I believe that the players are training very hard against the next season and the boarding is still on the process of backing him with new signings to succeed. I trust Xabi to succeed at Real Madrid he might not win major trophies in his first season but his second season with Real Madrid wouldn't be very successful.