Paul Tisdale said he kept players on the field he was more disappointed with than Alex Gilbey and Ryan Watson, despite bringing the pair off at half time in the 1-1 draw with Grimsby.
The duo made way for Robbie Simpson and Baily Cargill at the interval, and it appeared to make an immediate impact, with Simpson heading home the equaliser barely 40 seconds after the restart.
Dons were lacklustre in the opening 45 minutes, Tisdale admitted, and needed a new direction fast, prompting his double swap, but he said the changes were tactical at half time, and that he left on players he felt were worse in a poor first half performance.
"They were both tactical changes," he said. "It's not always about making judgements on the players and not always substituting the worst players, but doing something that can instantly make a difference to the flow of the game.
"At half time, my decisions have to be decisive. I don't have much time to coach what happens in the first half. Alex Gilbey and Ryan Watson weren't necessarily the worst players on the pitch, I thought we were poor generally. Actually, there were players on the pitch I was really unhappy with.
"I've only got three or four minutes to get information across. I had to make a difference and what we did instantly got us moving. We didn't everything but score that second goal.
"I was very disappointed with the way we played in the first 20 minutes, but we discussed the points we failed on before the game. But I'm still learning about where we are as a team. All our talk and purpose is positive - designed to play football and score goals. But we didn't turn it into a fluid, energetic performance."