Boro recorded back-to-back league wins for the first time this season as Peter Hartley nodded home his first goal for the club before Michael Doughty wrapped up the points late on, cutting in from the left and rifling home.
The hosts rode their luck, though, and had to rely on goalkeeper Chris Day to produce a string of fine saves - denying Kyle Bennett in the first half and James Hurst just before Doughty added a second.
"It's very harsh, we've played worse than that this season and won games, certainly drawn games," Barker said.
"You come away and say to the players there are things we need to improve but I can't fault their effort or desire.
"I thought we dominated probably 80 per cent of the game - most shots, crosses, corners, most possession by a mile and we've come away with nothing.
"If the first goal doesn't go in I think it's got 0-0 written all over it, we don't chase the game.
"If it doesn't work for the first half an hour we're not going to start lumping it, and it just took half an hour to find a way around it.
"I think they were over the moon the half-time whistle went but we could have done without it, we could have done with an extra 10 minutes because I felt we were on top.
"We overran them in the second half and we're disappointed we didn't score a goal."