The Iron were dominated for most of the match and could have conceded far more than 3 against an attacking Swans side, who took the game to their opponents.
Adkins told the Scunthorpe official site: "We knew before the game that Swansea were an excellent footballing side and I felt we were in the match until they scored their first goal.
"Before then we had enjoyed a good period of possession and I felt their goal had come against the run of play.
"At 2-0 we were always in with a shout but poor defending from ourselves made it 3-0 with around ten minutes left, like on Friday when we lost to Blackpool.
"We were playing a very good side today, who defended resolutely but at times I felt we gave the ball away too cheaply."