be out of (one's) depth(redirected from be out of their depth)
be out of (one's) depth
To be in a field or situation that exceeds one's knowledge or ability. Of course she's out of her depth with 25 employees reporting to her—she had hardly any supervisory experience before you gave her the job! I asked Alex to consult on this project because it's a bit out of my depth.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.