Kubo insists La Real were the better team on the day.
He said: "It's a shame. Anyone who saw the match knows that we deserved to win. Unfortunately, the time change and everything that happened didn't help us.
"They scored a goal, we had two or three chances. They were lucky. In 90 minutes they arrived in the area once or twice. We were superior but what matters is the result."
On the race for Europe, Kubo added: "We have home games that we can win. This time we lost, these games are costing us in the standings."