Namely, that if you stand still in the Championship you will get caught and overtaken before you can do anything about it.
Birmingham are embroiled in a fight against relegation for the second season running, despite being mainstays of the promotion race in previous seasons.
United, by contrast, are aiming to secure a play-off place in their first season back in the second tier by winning their three remaining games.
“Birmingham fans will probably think the table is upside down with us and Millwall being up there and them being down there with Sunderland and Hull,” said the Blades manager.
“I don’t think anyone would have expected it but that is what can happen at Championship level if you don’t get it right and your form turns and players don’t produce what they’ve been brought in to produce.
“We’ve done fantastically well the last 20 months and I want us to carry that on by driving us forward.
“You can’t take your eye off the ball or think you’ve cracked it. We’ve enjoyed being in the limelight, we’ve enjoyed being talked about in a positive way.
“But you’ve got to keep going, you’ve got to keep moving forward, trying to squeeze as much out of the football club as possible, whether that’s the staff, the facilities and more importantly the players; asking what we can we improve?
“When it comes to the end of the season we’ll have learnt some valuable lessons and what we need to do next season in all departments to be better.
“There are some huge clubs at the bottom of the division and it just shows you, if you do get into a freefall it’s difficult to turn it around.”