Manager Paul Warne on the slide hitting Rotherham United's promotion hopes
The Millers were looking good for League One promotion until hitting a miserable run of form in March that has seen them win only one of their last seven third-tier outings.
Concern was exacerbated by the poorness of the display in a 3-0 Tuesday defeat at Portsmouth.
When Warne was asked soon after the final whistle why performances had slipped so much from the high standards of earlier in the campaign, he said: "I don't know. It's the same group. I haven't got any excuses.
"We prepare the same, we train the same, we speak to them (the players) the same, we recover the same.
"That's my answer. It's not a very good answer. The fans aren't going to be buzzing with that."
Rotherham remain third in the table and, with a game in hand, can still go above MK Dons into an automatic-promotion spot if they rediscover their winning touch.
The next of their last five matches is at home to Ipswich Town on Saturday when the manager is likely to make changes to his starting 11.
"We are going to have to go back to the drawing board and look at something else," he said. "We are going to have to give other players an opportunity."