lose (one's) edge

To lose the skills, conviction, or energy that helped make one a success before. At one point I was considered one of the best tennis players in North America, but I lost my edge during college.

lose your edge

COMMON If someone or something loses their edge, they no longer have the special skills, qualities or advantages that they had in the past. As a company, they had lost their competitive edge. Its critics say the magazine is out of date and has lost its edge. Note: If a sword or knife has lost its edge, it is blunt.