There was a time when James L. Brooks was a sure thing. Writer/director of Terms of Endearment and Broadcast News, co-creator of The Simpsons. But since As Good As It Gets (I would argue THAT film is overrated), he has been on a downhill trajectory. How Do You Know is just more proof that he should take his money and live out the rest of his life on a tropical beach.
Resse Witherspoon's Lisa is a former star softball player cut from the national team, though we never see her actually playing softball. She has to decide between Owen Wilson's major league pitcher Matty (though we never actually see him playing baseball), and Paul Rudd's recently indicted corporate executive (though we never learn why he was indicted). There's a lot of things that are left out of this movie, not the least of which a question mark in the title.
This is just a sloppy movie. It's incredibly broad, and not nice to look at. Matty is a complete louse, and Rudd's George doesn't have a backbone. If I was Lisa, I would choose to be single. In fact, the whole affair looks and feels like TV (yes, that's a slight). Brooks is a veteran of both mediums, and should know the difference between the two.