I don't think it's as bad as people say, and perhaps the reason is because Real Madrid lost to PSG in the Club World Cup, which has led people to say that Real Madrid's performance has been very poor since Xabi Alonso took over....
If everyone understood that the reason was that Real had a series of injuries, then why didn't Perez give Ancelotti another chance? So Perez didn't think so, and he thinks that Real is capable of winning without these players, since he is ready to change the coach. Real has become better in what? They were good in attack, the problem was in defense, and so far nothing has changed in this. And we will be able to evaluate Alonso's capabilities very soon, the first 10 rounds will be enough to understand whether they can compete with Barcelona or not.
... If injuries were the main excuse, then swapping Ancelotti for Alonso feels more like a PR move than a tactical fix. Perez probably sees it differently — maybe he thinks a fresh face in the dugout will magically patch up defensive leaks, but unless Alonso can turn those centre-backs into prime Ramos & Pepe overnight, the same problems will show up.
Real’s attack was never the issue — Vinícius, Rodrygo, Bellingham, they’re all delivering. The problem is that every counter-attack against them feels like a mini heart attack for fans. If Alonso can tighten the back line and add some structure without killing their attacking flow, then yeah, maybe they can go toe-to-toe with Barca.