What constitutes ineffective assistance to the court in granting probation to a defendant?

Meaux next asserts that his counsel provided ineffective assistance by failing to object to the court's purported reliance on factors occurring subsequent to the original grant of probation and failure to consider mitigating circumstances. He correctly points out that "a defense attorney who fails to adequately understand the available sentencing alternatives, promote their proper application, or pursue the most advantageous disposition for his client may be found incompetent." (People v. Scott, supra, 9 Cal.4th at p. 351.)