Meat Loaf  argues that "2 out of 3 ain’t bad" but it does not work in Legal Malpractice. Proving that defendant was your attorney, and that defendant breached a duty of care is insufficient..  You must prove proximate cause as well.  There is little so heartbreaking as a trial verdict in which the first and second questions are answered "yes" by the jury, only to have them say no to:  Was this deviation the proximate cause of plaintiff’s injury?"  

Here is a NJ case on the subject. "In short, there was no evidence of any damages, apart from the failure to pay the note. There was no evidence of the value of the assets of the business, the value of the leasehold, or the value of the business at the time of Chang’s breach. Although plaintiffs proved the first two elements of a malpractice action, an attorney-client relationship and a breach of the duty of care, they failed to prove the third element, proximate causation of damages. Conklin v. Weisman, 145 N.J. 395, 416 (1996). "