In four of their last five matches they have conceded from dead-ball situations and the Reds boss feels most of the goals were preventable.
But after three successive clean sheets at the start of the season, there is a growing perception that Liverpool can be exposed at corners and free-kicks, as the likes of Newcastle, Crystal Palace, Sunderland and Manchester United have demonstrated.
"The more you concede at set-pieces the more you will (gain a reputation)," said Rodgers, who has been tackling the issue with his players this week.
"It's just concentration. The ball that came into the box against Newcastle was quite a straightforward one and we just didn't defend it well enough. We went to sleep a little bit.
"I was annoyed at the Crystal Palace one because even though the game was over (it was 3-0 at the time) it was still a goal from a set-piece that you shouldn't concede.
"But it's something that we've worked on and talked about this week in terms of our defensive mentality.
"We started the season with three clean sheets and we just need to get back to that mentality because we know that we can get goals.
"It is something we need to improve on."
Already this season Liverpool have had injuries to the likes of Glen Johnson, Daniel Agger and Jose Enrique and undergone a switch to three central defenders.
But Rodgers insists the changes are not to blame for their frailties.
"No, because from a set-piece you are given a job and I think it should be the simplest part of the game in terms of the ball is not moving," he added.
"If you analyse the goals from set-pieces the Southampton goal we just lost our marker and didn't do our job properly on the post.
"The goal we conceded against Manchester United away was from a simple ball into the box from a corner and we lost our man - that was a duel, one v one.
"The goal last week (at Newcastle) was a straightforward ball into the box and we switched off at the back post and the guy got in and scored.
"Again it is individuals. We have coped with set-pieces in the first few games - you just have to ensure every single game your concentration is right or you will concede a goal."
Liverpool sit third in the table heading into the weekend but their recent record against visitors West Brom underlines where they need to improve.
The Baggies have won the last three league encounters and Rodgers knows his side have to improve their consistency and win games like this one to maintain their progress.
It is why he is reluctant to talk about a top-four finish, never mind making an unexpected title challenge.
"We have still got a lot of work to do," he said.
"We will always look to improve our performance level but while we are picking up results and are finding ways to improve that performance level of course I'm happy.
"We all understand that we needed to improve. When I came in here, the club finished eighth in the Premier League and last year we were seventh.
"We've still got huge strides to make but I think it's pretty clear in the work that the players are putting in.
"If you look at Champions League level we know we've got a bit of work to do but it's about building here, that's the key.
"There's not going to be a quick fix. We've got to build towards that level so that it can be sustainable in the longer term.
"The squad will evolve, you don't need to be a rocket scientist to see that.
"I think that the minute you feel you're happy with what you've got maybe that bit of complacency will set in."