At the same time, I suspect that LSAT score does indeed predict success in law practice. There are several reasons for this correlation:
1. Reading Comprehension. RC is a a third of the LSAT score. RC is important in law school because it helpf to build your foundation of legal reasoning and analysis. RC is also a critical skill in law practice. Simply, the devil is in the details. This means you have to be able to grasp what you read strategically. But you also have to be able to read carefully enough to discern pviotal facts and statements, in order to maximize your use of what you read. In law practice, we spend hours reviewing contracts, discovery materials and other documents. An entire outcome can turn upon a single fact discovered as a result of plowing through a rich field of information. And you can quickly lose, if you fail to take note of the important piece(s) of information. Reading is arguably one of the most critical skills a lawyer can have.
2. Logical Reasoning. LR is another third of the LSAT score. In order to make and analyze effective arguments, you must be able to reason logically. LR is important in law school because it enables you to follow the legal arguments made in the materials you read, and replicate those argument styles at exam-time. It's important in law practice because, well think about it. How far would an illogical lawyer get with a client, or a judge? Sounds pretty silly, doesn't it? A lawyer has to be logical in his/her approach to everything we do. It's just logical.
3. Analytical Reasoning, a/k/a "logic games". AR is the final third of your LSAT score. AR is important in law school because in many of the cases you read, which are teaching tools, there are numerous disparate fact patterns, disjointed analyses, and sometimes poorly edited cases. All of this requires the law student to grasp a group of disparate things simultaneously and somehow keep track of and make sense of them all. Law practice is like this is well. You are rarely presented with a straightforward set of facts. Instead, you are given partial facts (sometimes the client tells you only facts in their favor) and you have to dig for the rest. Further, often many laws are implicated by a single set of facts. In a commercial situation, for example, you may be required to anticipate contractual issues. But you may also need to analyze that situration for antitrust and FTC Act issues, or other issues. You have to be comfortable with multi-variable analysis, that is juggling many balls, plates and chairs, in the air at the same time.
So, what if you fared poorly on the LSAT? Does it mean that you are ill-suited for law school and the practice of law? Perhaps. But it could also mean that you will simply have to work harder at all of the above than your peers. Intelligence is a function of not only your ability to solve problems, but also how quickly you can solve them. And there are all kinds of intelligence. And given enough time, anyone can solve any problem. As the old hypothetical goes, if you placed a hundred chimpanzees at keyboards, eventually you would end up with a novel.
So, I wouldn't worry too much if you didn't ace the LSAT. Certainly, it will affect your ability to gain acceptance into law school. However, once you're in, forget about it. Use your LSAT performance as a subtle remainder that you will have to work a bit harder than the next person. But that's what law practice is like. In many cases, I'm presented with legal situations with which I have little familiarity. But I can get familiar, if I am willing to invest the time in learning the facts and the law. I consult with colleagues to check my thinking. I review all of it, again and again. And eventually, I am able to master the particular matter. That's why they call it the "practice" of law. It means "practice makes perfect." And, in my humble opinion, your clients deserve perfection.
So the LSAT may be a predictor of your success as a lawyer. But remember, it's a standardized test. And any standardized test can be mastered, if the test taker is given enough time. Raw intelligence can help you succeed in law school. But hard work, dedication and perserverance can also go a long way toward success and a fulfilling career as a lawyer.