The former Villarreal goalkeeper joined Chelsea this week for a fee of £20m.
Tena said today: “One of the most important things in football is detecting when a player has the talent and is ready to make the jump to the first team. We knew it and we had complete confidence, although he could make some mistakes, we all make them, even adults.
"Sad because we didn't want Jörgensen to leave, the idea was to have a goalkeeper for many years, because one of the things that was difficult for us to get from the academy was a goalkeeper and when we got him and we thought that the second one was going to be better than the first (season), surely there would be increased value.
"Filip's will was to take advantage of the opportunity, he told us that he wanted to leave, after wanting him to stay we are also people and in this case we have received a transfer and I hope he is very successful."
Tena also confirmed defender Jorge Cuenca was in London for a medical with Fulham.
He added, “Jorge trained the last day yesterday afternoon and is traveling to the Fulham camp, he has to pass the medical examination and when the time is right we will make it official if everything is ok."