Termination due to bad performance reviews and unemployment benefits

One of the large employer's favorite ways to get rid of an employee, for a lawful or unlawful reason (i.e. due to discrimination or retaliation) is to start creating a record of poor performance, through series of negative performance evaluations, warnings, and PIP's (performance improvement plans). Since the manager has pretty much full discretion and allowed to exercise his/her judgment in evaluating an employee's performance, driving an employee out that way for fabricated performance issues is relatively easy.  

Last week we represented a former employee of Well Fargo Bank at unemployment benefits appeal hearing, who has been terminated for alleged poor performance after receiving an award for outstanding 5 years service with the company just a few months before being fired. He was fired shortly after turning fifty five. Our client's manager written him up twice before terminating him for alleged inaccuracies in his work. Reversing the denial of unemployment benefits by EDD and awarding benefits to our client, the appeals board reiterated yet again that "mere inefficiency, unsatisfactory conduct, poor performance as a result of inabiltiy or incapacity, isolated instances of ordinary negligence or inadvertance, or good faith errors in judgment or discretion are not misconduct within the meaning of unemployment insurance code that would disqualify claimant from unemployment benefits."   

I can smell age discrimination all over this termination. The question is whether we will have sufficient evidence to prove it when we file a wrongful termination lawsuit.