Thanks for your question. That is a more difficult question than you might expect. A win / loss record really refers to the lawyer's success rate. However, what is defined as success in any given case will be defined by its particular circumstances. In a criminal defense case, for example, a successful outcome is not always defined as an acquittal. In some cases an acquittal is near impossible. However, that does not mean that the case cannot be dealt with with a "successful" result.
For example, a client with a long criminal record facing another charge where the case against him is overwhelming may define success as any outcome that does not result in jail time — a result that may be very difficult to achieve. Or what about the lawyer who tries a case, receives a terrible legal ruling, resulting in a conviction, and then has that loss later overturned on appeal?
Or what if the jury returns a verdict of not guilty for two counts, but guilty on another count, or even on a lesser included offense?
Although it may not be possible to get an acquittal in every case, the lawyer may be "successful" in helping the client attain his goal. Is such an outcome a win or a loss? In the examples above, both the lawyer and client may consider it a win. What if the lawyer considered it a loss even though he helped his client attain the desired outcome?
With civil cases, like personal injury claims, over 90% of cases end up in a settlement. A settlement usually involves both parties compromising the amounts involved, and sometimes doesn't even include an admission of liability on either side - so you can't claim that one side or another 'won" or "lost" the case.
This example demonstrates that the term "win / loss record" is not a meaningful one. Rather, information relating to a lawyer's ability to achieve the client's goals (which may be different from case to case), listening skills, communication skills, approach to a case, and experience are more helpful in selecting a good lawyer.