lose a step
lose a step
To become less quick, skilled, or adept at something as one ages. Usually used in reference to sports. OK, so maybe he's lost a step over the course of his career, but he's one of the best players we've got left in our injury-decimated lineup. Everyone's saying that she's lost a step since her injury, but I don't think that's true.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.