out of practice
No longer used to doing something, no longer adept for lack of doing something, as in Mom hadn't baked a cake in years—she said she was out of practice. [Late 1800s] Also see in practice.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.