The U’s had opportunities to win both games, but followed up a 1-1 draw at home to Burton Albion with a 1-0 defeat at Southend United on Saturday.
It was the latter result which particularly upset Wilder, who felt the visitors were lacking a streetwise streak, which had been evident in getting a stoppage-time winner at Bradford City last month.
The United manager said: “I don’t know what they were thinking, but the teams that achieve this year will show the things we didn’t (against Southend).
“That isn’t ability, shape or organisation, it’s doing the right things in the big moments of the game.”
He added: “It’s a situation where (Southend’s) players have got that little bit more know-how and nous and mental ability to make the right decisions at the right time.”
Meanwhile, Lewis Montrose, who was influential in the win at Bradford, could be back in contention for this Saturday’s home clash with Bristol Rovers after missing three games with a hamstring injury.
But Wilder says it is down to everyone in the squad to develop the knack of winning tight games.
“The players have got to learn, (Adam) Chapman’s got to learn, (Damian) Batt and Alfie Potter have to do that if they’re going to progress,” he said.
“I’m not just pointing the finger at them, all of them have to learn to come here and get a result.
“It kills us – you can’t keep missing those chances and then switch off in the 85th minute.
“You have to go with the players who are in your club. “There won’t be a lot of changes as we all know, but we have to wise up, because I want to achieve here.”
The two results saw United slip into the bottom half of the npower League Two table, seven points adrift of the play-off places.
Wilder acknowledged the last week had been a setback, but with 17 games to go, he is confident there is time to turn it around, if they can take the criticism on board.
He said: “Tuesday and Saturday damaged us, but we have to recover and take it on board.
“If we don’t, then we’ll play well and this will come up again.
“Have we got the absolute attitude to say ‘here we go, get what you deserve out of a game’?
“That’s what we have to do.”