An Abdon Prats penalty proved the winner for Mallorca on the night.
Arrasate later said, "It's a great victory, necessary, deserved and meritorious. We made eight changes, but in the end it was not me who was right, but them, with the game, because they interpreted well what we had to do.
"We have the squad for it and there are still some who have not participated much who will. It's a team victory that gives us a different feeling because of the rival, because of how we played and because it was at home.
"Playing a good match against a great rival and with your fans was necessary. It's a victory that will give us confidence. These are the things that happen in football. Three days ago I was here feeling terribly upset and now I'm happy.
"This is what football is like and we have to keep going. Now we have three games away from home, but if we continue at today's level I'm sure we can get good results away from home. That's the objective."
On Sergi Darder's performance, he added: "He enjoyed playing a great match, he defended and attacked well. Sergi suits a special ecosystem, he can play in many positions depending on the system. He played a good match and I'm happy for him."