Russell Martin felt the disappointing display at Newport County was evidence that his MK Dons side is still a work-in-progress.
The Dons were knocked out of the Leasing.com Trophy on Tuesday evening after a 3-0 defeat at Rodney Parade.
Martin had made seven changes to his starting XI for the trip to South Wales but didn’t use the amount of alterations as an excuse – instead, he bemoaned the execution and mentality of his side in the first half.
“The game was over after that first 45 minutes,” Martin said in his post-match press conference.
“We’ve not had a lot of chance to try anything different since taking over so tonight was an opportunity to do that but it was still a team that should have been good enough to compete. We saw it as a team that could win the game but some have not taken the opportunity they have been given.
“It's not an easy place to come but we cannot concede goals like that or fail to compete in our box, as we did. Two of those goals came from people not picking up their players and that's not acceptable.
“What disappoints me more, though, is how we reacted to conceding. We looked wobbly again and that's down to mentality. It's one of the reasons we are where we are in the league and it’s not acceptable anymore. If we are to become a better team, we cannot keep doing that.
“We were a bit better in the second half. We were brave and tried to pass on a poor pitch. We had some half chances but the game was over after the first-half performance.”
While disappointed with some of the performances, Martin was assured in his post-match debrief and insisted he won’t make rash and emotional decisions on individuals based off one poor display.
“It's disappointing some didn't take their opportunity tonight but it’s important not to judge people off one performance. We're learning about players individually all the time, and tonight is no different.
“It has shown how much work we still have to do with certain individuals and in certain areas. It shows, although we've found some form, we've not cracked anything and there is a lot of work to do.
“I've got complete confidence and belief in these guys, despite tonight. Now we need to make sure we get back to it on Saturday.”
MK Dons return to Sky Bet League One action this Saturday when they travel to the St Andrew's Trillion Trophy Stadium to take on Coventry City.
Tickets are priced at £20 adults, £15 seniors/under-22s and £10 under-18s while nurses and members of the armed forces can purchase tickets at a discounted rate of £15.
Official Away Travel is available for this fixture, with coach spaces priced at £14 Season Ticket holders and members and £15 all other supporters. Coaches will depart Stadium MK at 12noon.
To book tickets click HERE, visit the Box Office at Stadium MK or call 0333 200 5343. Tickets will be available to buy from the Club until 5pm on Friday.