Yoshinobu Yamamoto, RHP
While not a proven commodity in Major League Baseball, Yoshinobu Yamamoto has certainly established himself in his home country of Japan and has rapidly become one of the hottest free agents on the market.
He's only 25 years old, but the right-hander has already played seven seasons of professional baseball and has utterly dominated the Japan Pacific League in recent years. Not only is he a five-time All-Star, but Yamamoto has collected multiple Eiji Sawamura Awards (the league's version of the Cy Young) as well as multiple league MVP trophies.
Over the last three seasons with the Orix Buffaloes, who also once employed Mastaka Yoshida, Yamamoto has gone 49-16 with a ridiculous 1.44 ERA, recording 580 strikeouts against just 110 walks in 550.2 innings.
Now, Boston obviously won't be the only team interested in acquiring this potentially game-changing superstar. The New York Yankees have already shown plenty of interest, and several other clubs have made the trip overseas to get an up-close look.
It will definitely take quite a bit of cash to bring him to Boston, which could mean losing out on some other players. But if Yamamoto can be anything even close to what he's been in Japan, it might just be worth it.