Imanol left out potential departures Mikel Merino and Carlos Fernandez, with Martin Zubimendi also struggling for fitness on the day.
He later said: "Of course I was disappointed by what happened, especially the first 10 minutes. I noticed a lot of pressure and tension. Then, we took a step forward, we were better, there were moments in which we got out of the good pressure and we have created some situations, although not very clear.
"And then, with the match tied, if we are not brilliant with the ball, we cannot give away the two throw-ins that we have given away and that have ended in their two goals."
On the role of Zubimendi, he said: "The first two changes have been more tactical, but Martín has not started as a starter because yesterday he told me that he was not fit, he has experienced incredible pressure, but today I told him to make an effort, because of the card that Urko has seen.
"Of course it worries me, because we haven't played the game we wanted, we have conceded two goals, there have been many players who haven't lasted the 90 minutes, we haven't played a good game in front of our fans..."
Imanol also reflected: "It hasn't been complicated at all, it's what happens every year, to all the coaches, the clubs and the sports directors. Every summer there is movement. Merino and Le Normand? There are no two players like those. And no longer I'll tell you if Zubimendi leaves us at the last moment.
"They are irreplaceable players. Because of what they have done, we are talking about Le Normand leaving, Arsenal want Merino and Liverpool were willing to pay the clause for Zubimendi. We can always look for an excuse when Merino and Le Normand are not there if things don't work out for us."