Real Madrid axed Xabi two days after losing the Super Cup final to Barca in Jeddah, Saudi Arabia.
Speaking to RAC-1, Deco said: "We focus on our own business. We don't think about what's happening at other clubs, but with the pressure at Barcelona and Real Madrid, it's always complicated, and when results don't come, the coaches are the first to suffer. It's a bit surprising because it hasn't been that long."
Deco continued: "They lost the Super Cup, but they're four points behind in La Liga, and they're doing well in the Champions League. But I prefer not to comment from the outside, and I don't like to because I don't know what's going on day-to-day.
"These aren't our issues. When you ask me about Hansi Flick, the feeling was much stronger than the numbers. With Hansi, we knew the good times would return."
Regarding Real's caretaker appointment, Alvaro Arbeloa, he added: "I understand that Real Madrid is very important, but we're focused on our own thing. I don't know if Arbeloa is a good coach. I don't know him. I don't know if it's a permanent move or not, and I don't want to dwell too long on Madrid."