Shrewsbury boss Micky Mellon blamed his team selection for the loss at Walsall which leaves Town still needing three points to ensure League One safety.
Mellon's men are just four points clear of Blackpool, in 21st place, with games against Peterborough and Swindon left.
Mellon blamed Town's switch to a 3-5-2 formation on Tuesday night, which he abandoned after just 17 minutes.
"I take responsibility because, in hindsight, I should never have played it," Mellon told BBC Radio Shropshire.
"I could see right away it just wasn't going to work."
Having gone one down, Mellon sacrificed on-loan Wigan Athletic defender Jack Hendry to revert to a flat back four.
Then, with his side 2-0 down at the break, he made two more early second-half changes, bringing on Larnell Cole and Shaun Whalley in place of James Wesolowski and Jean-Louis Akpa Akpro.
Despite their improved display over the final third of the game, following Mat Sadler's 60th-minute far-post header, Mellon was disappointed that they did not play the whole match with the same intensity.
"If we had started the same way we played in the second half, then it could have been a different occasion," he said.
"I just want to have some consistency in selection and hope that the lads can step forward from the last performance and keep things going."