At a total cost exceeding $100 million, Daisuke Matsuzaka is anything but a bargain for the Boston Red Sox. Oh, they are happy with their winter coup of the Japanese ace, to be sure. Despite a couple of rough starts, Matsuzaka is 6-2 with a 4.06 ERA and a team-leading 62 IP, marks that rank well above average in the AL East.

Now consider what Hideki Okajima, the other Japanese pitcher the Red Sox signed, has done while working for a bargain-basement deal of $2.5 million over two years: 21 2/3 IP, 11 hits allowed, 24 strikeouts, four walks, 0.42 ERA and a peace of mind for manager Terry Francona and Red Sox fans everywhere that you literally can't put a price on. (Francona's approval ratings in the Nation haven't been this high in years.)

The signing of Okajima was so eclipsed by the Matsuzaka hype that you may think he came out of nowhere. In fact, Okajima was the setup man for the Japan League champion Hokkaido Nippon Ham Fighters last season, posting a 2.14 ERA. Stateside, he has not been scored on after giving up a home run to the first batter he faced in his major-league career, Royals catcher John Buck on April 2.

Since then, Okajima has emerged as a lockdown setup man who, in tandem with closer Jon Papelbon, effectively shortens the game to seven innings for Boston's opponents. Far from being a Mike Myers-style LOOGY (Left-handed One-Out GuY), Okajima uses a devastating changeup -- the "Okie-Dokie" -- to put away both left-handed and right-handed hitters. Check out his splits:

Okajima vs. Righties: 47 PAs, .174 BA.191 OBP, .239 Slg.
Okajima vs. Lefties: 31 PAs, .107 BA, .194 OBP, .107 Slg.

It's this versatility that makes the 31-year-old veteran of the Japanese major leagues invaluable to Francona. Consider that the Boston skipper hasn't had to worry about overworking his ace closer, Papelbon, who had a shoulder injury last season; Papelbon hasn't had to pitch in the eighth inning since April 13, and hasn't been asked to record more than three outs in an appearance since April 8.

Okajima also has proven to be a reliable sub for Papelbon, saving games on April 20 against the Yankees and on May 17 against the Tigers, the latter appearance being the second game of a doubleheader in which he had already pitched the eighth inning of the opener. Put it all together and you get one of the best relief performances in the American League this season.

According to FanGraphs.com, which ranks relievers according to a wonderful and aptly-named statistic called "Win Probability Added," Okajima ranks as the fourth most effective reliever in the AL, behind Papelbon, Seattle's J.J. Putz and Tampa Bay's Al Reyes. Baseball Prospectus has a similar statistic for relievers called "Win Expectation above Replacement," which is adjusted for difficulty of lineups faced. BP has the same top five, though it puts Okajima a tick ahead of Papelbon.

That's not a bad return so far on a $2.5 million investment.