But Birmingham's problems are no such secret and Manchester United exploited them to the full at Old Trafford.
Thrashed 7-0 by Liverpool in the quarter-finals of the FA Cup at St Andrew's on Tuesday, the Blues could only improve.
A goal down after 134 seconds and 2-0 behind in the 15th minute, Birmingham manager Steve Bruce must have feared another horror show with his side staring relegation from the Premiership firmly in the face.
His team were eventually saved by some profligate first-half finishing by the Red Devils from which they regained some confidence to come back into the game after the interval.
They could even have made United sweat, but for missing two gilt-edged chances in the last nine minutes.
Bruce must have feared the worst when United went ahead in the third minute.
Martin Latka brought down Cristiano Ronaldo 25 yards from goal to the right of the Birmingham penalty area.
Up stepped Ryan Giggs to fire in a superb swerving free-kick - the ball being turned on to the post by goalkeeper Maik Taylor before rebounding into the back of the net off his head.
Giggs was denied by Taylor from another free-kick soon after, although United goalkeeper Edwin Van der Sar had to be alert to turn behind Emile Heskey's header and then keep out a Dudley Campbell shot.
Hopes of a Birmingham revival crumbled in the 15th minute when United made it 2-0 with a peach of a goal.
Giggs nutmegged Damien Johnson as he cut in from the left to find Wayne Rooney, who played the perfect through ball on for the Welshman to score with a left-foot tap-in when he continued his run into the box beyond an almost non-existent Blues backline.
Rooney could easily have had two goals before the break.
In the 31st minute, superb work by Ronaldo in the middle of the park saw him find Giggs, whose cheeky backheel sent Rooney racing clear.
He continued his run into the Birmingham penalty area but then hit his left-foot shot wide of the far post from 12 yards.
Two minutes later, Ronaldo's through ball sent Rooney racing clear a second time, but with only Taylor to beat he hit his right-foot shot wide from the edge of the box.
United let their grip on the game slip after the interval although it took Blues 36 minutes to find a way through.
Jermaine Pennant's corner to the far post found Jiri Jarosik unmarked. He knocked the ball back to Heskey, who ballooned his shot high over the bar from ten yards.
That shock stung United into life and they made it 3-0 when Ronaldo's header sent Rooney away through the middle and he scored with a right-foot shot from just inside the box.
Birmingham went on to miss another golden opportunity seconds later when, after they failed to capitalise on shambolic United defending, Stephen Clemence's close-range drive was brilliantly kept out by Van der Sar.