It is not a whole lot of fun to work for a manager who plays the blame game, but in a technical sense, you can delegate authority, but not responsibility. When you are delegating authority, you are delegating the power to get a job done, but the responsibility for getting it done still reverts back to you.
However, even if part of this failure arguably rests on your shoulders, your manager should be directing his energy toward solutions rather than problems. He should be focusing on the steps that need to be taken in order to bring the project up to par, and giving you guidance as to the ways to delegate more effectively in the future.
The irony is that if he originally delegated this project to you, then some of the responsibility for its failure is his as well. The problem is that when people are running around trying to figure out who is to blame for what, all they are doing is generating dissatisfaction, disloyalty, and distrust, and this increases the likelihood that future projects will fall short of the mark as well.
At this point, you should meet with your manager to discuss the ways to bring this project to a successful completion. If he balks, no one can blame you for having real questions about his skills as a manager.
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