"We've got to regroup as a team and start putting things right," Platt told BBC Essex.
"Defending is not only the back four, it's the whole team and we were such a hard unit to break down prior to those two games."
He added: "If you get beaten one-nil or by the odd goal you can accept it, but getting beaten five or six without reply is just poor."
Saturday's heavy defeat followed a 7-0 exit from the FA Cup at the hands of Preston North End at the beginning of January.
Despite recent results, Platt believes Colchester can rediscover their form and still challenge Norwich for an automatic promotion place.
"Other than those two games, our previous form showed we can do that," he said.
"We've done it against the top teams, so there's no reason why we can't do it again."
Source: BBC Sport