Dean Cox's early strike for the visitors means Boro have won just once in six matches.
Smith said: "I thought it was a very tentative start. We've had three weeks off and there were all the signs of a group that hadn't played for a while, which we were certainly hoping wasn't going to happen.
"The players are fully aware of their lack of performance, and it's down to them - and me of course, massively - to make sure there's a big turnaround.
"The goal was sloppy from our point of view. It made things much easier for them, we gave a good response, but there wasn't enough cutting edge in front of their goal.
"We were expecting to regroup at half-time and get out of the traps in the second period but it never happened.
"We got the ball in exciting areas but our choices weren't good enough and our quality was lacking.
"At home we've got to make more of the moments we're getting. We're all very aware how poor our form is at home, it's become an Achilles heel to our season."