Gary Johnson made 25 loan or permanent signings during his fairly brief time in charge of the club but had already admitted that a number of those he brought in had failed to meet his expectations.
Holt, part of the caretaker management team along with David Lee, told BBC Radio Northampton: "Any new manager that comes in won't fancy a lot of the players the old boss signed.
"He'll want to put his own stamp on things. A lot of the players know they haven't done enough and have probably let their manager down."