There are many links in the chain of generating new clients from the Internet. If any one of these links is weak, or broken, your likelihood of having success will be significantly diminished:
Traffic
Law firm web marketing has to start with traffic. Obviously, if you don't get traffic to your website, it is very unlikely that you will be able to generate new business. But traffic for the sake of traffic isn't enough. If visitors for your site aren't looking for the information or services that you provide, they will likely leave, or bounce off, your site without taking any action. Therefore, your website traffic needs to be targeted. Targeted traffic to your law firm website is the first link in the law firm web marketing chain.
Leads
Leads, or conversions, are the portion of targeted traffic that takes some sort of action on your law firm website. A conversion might be a phone call to your firm, a request for a consultation, or some other informational request (i.e. whitepaper, guide, e-book). Having several well-placed calls to action, will increase the likelihood of a visitor to convert into a lead. Converting traffic into leads is the second link in the law firm web marketing chain.
Clients
Finally, in order to generate a positive return on investment, your law firm web marketing efforts ultimately must generate clients. While having traffic and leads is a good start, those leads have to turn into new revenue for your law firm. The likelihood of your law firm website traffic turning into a new client for your law firm depends on all these links working effectively and efficiently. If you're not getting visitors, then your conversion optimization is meaningless. If you're not converting traffic into leads, then your monthly visitor metrics become meaningless. Finally, your phone could be ringing off the hook but if those calls aren't looking for the services that you provide, again, your law firm web marketing is probably failing.