Here's what they said about the pick:
Leshoure is a little different tact for that plan than many thought just a month or so ago, when it was assumed that a speedy, slender third-down runner was the best option. But why take the ball out of Jackson's hands on third-down? Years of abuse have added up, and Jackson's talent is wasted pushing him between the tackles. Jackson is the best so-called third-down back the Rams are going get... and they already have him. Leshoure will take over many of the first- and second-down carries, or the between the tackles stuff.
I love this pick. A lot. It's perfect, really. The Rams need a running game with Sam Bradfordimproving as a young player and RB Steven Jackson is the exception not the rule when it comes to lasting this long. He's likely on the down hill side of his career and Leshoure can help extend his life in the league. Plus, some argue Leshoure is the best back in this draft.
For the full explanation of this pick, check out Mocking The Draft.