The home rearguard – featuring the club’s first-choice centre-backs and a senior left-back – endured a troublesome night in the club’s Checkatrade Trophy exit on penalties to Manchester City Under-21s, with the youthful Blues’ pace and movement causing them major problems.
The Reds bowed out 5-3 on penalties, but it was the leakage of three goals in a 3-3 draw, which took their concession count to nine goals in their past three matches, which was more disconcerting to Winkler.
The German said: “It is too much, but I do not want to talk about the back four, but the team. We always say we want to defend as a team as we did in the first five or six matches.
“We have to be more ruthless and clinical in front of goal and defend better as a team. Defending in our style starts with the strikers.”
Tuesday’s defeat, albeit on penalties, ended Barnsley’s proud 16-match unbeaten Oakwell run, stretching back to mid-March.
For Winkler, a more painful consequence was the dashing of the club’s Wembley dreams, fresh from winning this competition in its guise as the Johnstone’s Paint Trophy in 2015-16.
He added: “We wanted to win and go to Wembley. Some of the lads have been to Wembley, but I have never been there.
“It would have been a good chance for me and now I have to buy a ticket.”
Tuesday’s occasion made for a memorable one for former Reds Under-23 development coach and caretaker manager Paul Harsley.
Putting partisanship aside, the City elite development squad coach was pleased to be reacquainted with several young players whom he nurtured, including Victor Adeboyejo and Jacob Brown, even if he did not want to witness too much of their talent.
“Victor scored the first goal and I had a little chat with Jacob Brown when he was going on and said: ‘you’d better not score as well’ because they were my front two, really,” Harsley quipped.
“But it is really pleasing to see lads who I worked with for a couple of years playing in League One on a regular basis. It is nice to see those lads going well.”