The Swansea winger's start to the campaign has been ruined by a thigh injury.
The problem kept the Spaniard sidelined for almost two months, and he then suffered a recurrence of the problem days after his comeback appearance against West Ham, which led to another month out.
The 28-year-old admits the setback left him at his lowest ebb but, after returning as a substitute in the Europa League defeat to Valencia, he is eager to reward manager Michael Laudrup for the faith he has shown in him during his recovery.
"This has been the worst moment of my career," he said. "Before I had injuries where being out for three weeks or one month was the worst I have had. This period has been the worst in my career.
"After the West Ham game, I had recovered from the first injury, I played 30 minutes and I felt good on the pitch.
"Two training sessions later I went to take a shot and the injury went again. That was very, very hard for me because after two months out already I had got back with the team and to be injured again was hard to take.
"But Michael always helped me, he spoke with me and supported me, he is very important to me.
"He told me he has confidence in me and my recovery, it's important for my mind to stay positive, but he's frustrated too because he's like me, the team needs all the players for all the games we have and I have been sat here.
"I have worked hard to recover but I've been unlucky. I want to do well for Michael Laudrup, the club, the physios, I feel the support they have given me."
But Laudrup has warned it will take a little bit of time for the Spain international to get back to his best.
"He was outstanding in pre-season. He was our best player. He started the season well and had a very good game against West Brom," said Laudrup.
"Now we have to get him back on the pitch.
"We are talking about it being a lot of weeks (since he played) so don't expect Pablo to now come into a game and show himself from the first moment.
"We have to bring him in during the next three, four or five games before we get him at his best.
"Right now, that is up to me to find the minutes in the different games."
Hernandez's next chance to get some game time under his belt will be against in-form Manchester City on Sunday.
Hernandez is familiar with several of City's players from his time in Spain and admits Swansea face a daunting task.
"I saw the Tottenham game," he said. "They have a big team with big players.
"I know some of them. Jesus Navas scored two, Alvaro Negredo scored two and Sergio Aguero, I know them from La Liga, and they have a lot more great players like Samir Nasri and Edin Dzeko.
"I also played with David Silva in Valencia, I played with Jesus Navas and Negredo in the national team one or two times.
"I have been impressed with them. They played well in Spain but with the change of the league, it's not easy because it's a different kind of football, more physical, but they have done very well in their first games. They are all big, big players."