The phrase 'improper performance of' is correct and usable in written English.
You can use it to refer to an inadequate execution of a task or skill. For example, "The improper performance of the goalkeeper's duties led to the team's defeat in the match."
In the Argentine Congress, two new impeachment complaints against all nine members of the court were filed today, joining 28 accusations of "improper performance" of duty already on file against individual justices.
The 28 pending complaints of "improper performance" of duty include the Menem arms case as well as the botched investigation of a terrorist attack on the Israeli Embassy here in 1992.
Payment to police officers or other public officials with a view to the improper performance of their duties may amount to a range of corruption offences – none of which carries a public interest defence.
An improper performance of displacement work (primary cementing) may cause both financial losses and environmental damage.
These acts of atonement involving human sacrifice were based on their belief that illness and natural disasters were forms of supernatural punishment for sins committed or for the improper performance of various sacred rituals.
High-liability risk specialties see more claims due to improper performance of a procedure, while low-liability risk specialties have more claims where the primary issue of concern is diagnostic error.
In other words, is feeling of improper performance a sole origin for the odd sensation?
Recently we learned that millions of dollars in improper performance bonuses were assigned to senior VA managers in 2007 and 2008 while hundreds of thousands of disability claims remained backlogged.
It is also important that you use great caution when performing these exercises since improper performance could result in injury.
No medical misadventure (23%) and improper performance were the next most frequently coded medical misadventures for this group of physicians.
The incident is being criminally investigated for negligence and causing serious harm to another person via "improper performance... [of] professional duties", according to Russian news outlet, TASS.
