The eye-raising run of the home team not winning in all meetings between AFC Wimbledon and the Greens continued at Home Park, with the Dons improving their hopes of making the Sky Bet League 2 play-offs by denting Argyle's own dreams of automatic promotion.
Despite Graham Carey hitting the crossbar in the opening minute of the game, the visitors went in ahead courtesy of a swift counter-attack, capped off by Lyle Taylor.
"I think we were the better team in the first half," said Adams. "I think we had the most opportunities in the first half, and they've really only scored with one counter attack. We knew that was their best option today - it was going to be the counter attack. That's how they got their first goal.
"It was poor defending from our point of view, but we've been saying that for a few weeks now. We haven't been able to take chances and we haven't defended properly. Overall in the 90 minutes we had a lot of good play."
The Pilgrims brought themselves level just after the hour, as Carey latched onto the end of Gary Sawyer's cross with a sweet left-footed finish. Derek's side pushed for a winner and were much the better side in the latter stages, but substitute Adebayo Akinfenwa headed home the winner late on as Argyle's defence failed to deal with a high, bouncing ball.
"We've obviously lost two really bad goals today," said Adams. "We said the same last week at Exeter: two games that we looked in good positions to win, with the amount of good play that we had, and opportunities, and we haven't been able to see out the game.
"I think the good play we've had, the opportunities we had, we should've gone on to win the game or even draw the game. It's two weeks in a row where we've been in very good positions, we've made individual errors and it's cost us.
"I can sit here and make all the excuses - we haven't taken the three points. I feel that at times today we played very well, but the aim of the game is to get three points. Defensively we've come up short."
Argyle once again squandered a positive position to fall to a defeat, and Adams is looking for players at both ends of the pitch to step up their performances from here until the season's end - along with a little bit of luck.
"We've created chances but we haven't been able to get that second goal," said Derek. "Overall, we've had enough opportunities to win the game, but it's a game where we've come away with nothing.
"We can't afford to keep conceding soft goals; we have to score an excellent goal. We haven't been given many free goals and I think that other teams have. Overall I thought the team showed a very good willingness to try and get the victory."