Martinez, who joined Wigan from Swansea in the summer, has now seen his side lose their last three games after an opening day Premier League victory over Aston Villa.
The Wigan boss made nine changes to the team that lost 5-0 to Manchester United on Saturday and said the replacements had let him down.
"As a professional footballer you need to be ready for the chance when it comes along. We can learn a lot from this defeat," he said.
"Those who have not been involved in the league games were given an opportunity tonight, but it was not good enough.
"Overall as a team and as individuals, we handed the game to Blackpool.
"They did not have to work hard for their goals, and it is very disappointing."
Meanwhile, Blackpool manager Ian Holloway was delighted with his side's performance.
"Just about everything went right," he said.
"We ordered the rain, and it came down just as they went out for their warm-up. I am not sure how many of them actually fancied it - but my lads did."
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