Five clean sheets and suddenly Birmingham City, ostensibly in decline until a month ago, are looking like a Premiership club in all but name.
The reasons for the revival are many — increased confidence, better luck, a good mix of youth and experience etc. — but Eric Black has no doubts why Birmingham have shown a marked improvement since the match at Derby County on October 21.
"The clean sheets, all five of them . . . that has been the key to it," Black said. And he should know. As assistant to Steve Bruce, the Birmingham manager, Black is keen to ensure that Birmingham build from the back, and avoid conceding goals by leaving the defenders exposed.
If it means a brand of football that is less pleasing to the eye, so be it.
But when Birmingham defeated Barnsley 2-0 on Saturday, their fifth Coca-Cola Championship victory on the run, the performance of the defenders was not lost on Black.
"I thought the back five again were exceptional," he said. "As long as we keep that clean sheet, I believe we have got enough to score a goal. Against Barnsley, we couldn't get the second one.
"With us not getting that second goal, the longer the game went on, the more Barnsley believed they could get back in it. Until that second goal goes in, which unfortunately, in this case, was right at the end, the game is never over.
"We had two or three opportunities before half time to put the game to bed. And it then became a little bit nervous the longer the game went on but it's still a good victory that keeps the good run going."
Previously, Birmingham's problem was that they pushed forward with little discipline. It looked good, and contributed to impressive victories, but it also caused embarrassing defeats. The 1-0 defeat to Norwich City on October 17 was Bruce's worst moment as the manager of Birmingham.
It is testimony to David Gold, the Birmingham chairman, that Bruce survived, but it was a close-run thing. A month on, and the picture at St Andrew's could hardly be more different.
"In this division, you can't afford to be losing goals," Black said. "I think we have got enough in the front six to score goals and if we have got that resiience and defending at the back, it is good. That has got to be the philosophy and we are getting our reward at the moment.
"The players deserve the credit. Initially we were trying to beat teams and trying to get extra men forward but we were leaving ourselves slightly exposed at the back. I think the priority now for the back four is to defend and they now know that. It is a no-risks approach. They defend, stay in their areas and play the ball with a bit of quality forward as quickly as possible and then we take it from there."
Of course, it was wise of Bruce to make better use of his experienced players. When Birmingham defeated Derby on October 21, the Birmingham manager turned to the likes of Stephen Clemence and Martin Taylor and demanded greater composure.
Taylor, who endured a miserable end to last season as Birmingham fought to avoid relegation, is producing perhaps his best form for the club. He cites the presence of older players who seem to complement the younger ones.
"There are the older lads like myself and Clem who are on the other side of 25, which is old in this team," Taylor said. "And, behind us, in goal, Maik Taylor has got a hell of a lot experience, which is great.
"So has Rahdi Jaidi [defender], who has played in two World Cups [for Tunisia]. He's been fantastic over the last few games.
"We've got experience in the squad but we have some young lads who haven't played at this level regularly so you do need to keep them on the right track. But there are players out there who have played a lot of games. Stephen Kelly [right back] has played quite a lot of games for Spurs, more than you think. You've got to pick up some good experience in games like that.
"You just need to pull together when it's not going great and I think we've been doing that over the last few games."