Hiroyuki Nakajima is one of the best free-agent shortstops available in 2013. Unfortunately, he's from the Japanese leagues, so the Cardinals haven't pursued him.
So long as you've watched this site and Viva El Birdos, you don't need to have followed the 2013 MLB rumor mill closely to know that Hiroyuki Nakajima, star shortstop of the Saitama Seibu Lions, is headed to America this year. I've made him into my Cardinals free agent cause of choice, which is why I'm so disappointed to report—passed along from Baseball Nation—that the Oakland Athletics and Arizona Diamondbacks are connected to them.
It's pretty easy to make the case for him. Nakajima was one of the top hitters in a hitting-starved Pacific League last year, and in this new dead-ball Japanese scoring environment last year's .311/.382/.451 line feels considerably more trustworthy than infielders did in the Kaz Matsui era. He hits doubles and home runs, he runs well, and if he's not a shortstop full-time he'd be an excellent starting-second-baseman-cum-Furcal's-caddy.
Unfortunately, it looks like he's going to be Oakland or Arizona's caddy, in a single-digit-millions-anually deal that won't go more than two or three years. Admittedly: I'm a huge Japanese baseball fan, and I'd root for the Cardinals to sign Nakajima even if he weren't very good. But I did the same thing with Norichika Aoki, last year, and he had a pretty great year, right?