"It wasn't the start that we wanted (in today's game), certainly the first half wasn't good enough," he said.
"The manager had a go at half-time, addressing the lads about how really unhappy we were with the performance in no uncertain terms.
"I think we got a reaction from the lads, it was good to see Josh Robertson come on again and I thought he did very well again, but the result has still gone the wrong way for us. It was a disappointing game and disappointing end to the season.
"We went 1-0 down and I think that showed how fragile the group are. We struggled for the rest of the first half, but we played better in the second period and looked like we could even nick an equaliser."
Striker Danny Elliott, who got off the mark for the Iron last week, scored for the second game in succession, and Plummer added: "I think that's another positive. Goals is what he's about. He did really well again today and he's getting those chances now."
Dion Sembie-Ferris came off with a knock, and Plummer said: "He's been carrying a foot problem for just about the whole time he's been with us. I think he'll be fine, and a few of the lads have been carrying knocks and injuries. Now is the time for them all to recuperate and get ready to come back for pre-season at the end of June."
See more from Chris Plummer and Danny Elliott on Iron Player.