Clearly frustrated after being in the play-off places for so long, Rangel believes that the past campaign was just another when the Swans 'failed.'
"Personally, I am so frustrated," he admitted.
"It's going to be a long summer because we have been punished in the main moment of the season.
"You can say it's been good season, but for me, to be honest, it's a disaster.
"It's another season where we have failed, simple as that.
"We had the perfect opportunity to get into the play-offs on Sunday.
"We hoped Blackpool would drop points and they did, but we didn't do our job.
"Once again we played a good game but we could not find a goal.
"I got over what happened after January because I had to," he added.
"I could have been a Europa League finalist now and obviously, when I saw Fulham get there, I was thinking about that and it was a little bit frustrating.
"But that's in the past now.
"I convinced myself after January to give 100 per cent for Swansea and I did that right up until the end of the season.
"The disappointment is that we failed to get where we wanted to be.
"I have a year on my contract and I don't know anything apart from that.
"If some club comes for me then we will speak about it, but this is not the time to talk about that.
"All I can do now is see what happens in the summer.
"Hopefully we can build a good squad which will get us where we want to be."