Who was the best free-agent signing in MLB?

By Gary Hill

The money was flowing for free-agent pitchers this past offseason. Zack Greinke secured a hefty $147 million deal from the Dodgers. Edwin Jackson took a four-year, $52 million contract from the Cubs and Anibal Sanchez agreed a five-year, $80 million deal from Detroit.

Dan Haren (one year, $13 million), Hiroki Kuroda (one year, $15 million), Ryan Dempster (two years, $26.5 million), Brandon McCarthy (two years, $15.5 million), Jeremy Guthrie (three years, $25 million), Hyun-Jin Ryu (six years, $36 million) and Joe Blanton (two years, $15 million) also secured lucrative contracts.

What do they all have in common? They all signed for a higher annual salary than the Mariners’ Hisashi Iwakuma did over the winter.

Yes, Joe Blanton and his 1-10 record and 5.87 ERA signed for more dollars than Iwakuma. Blanton coughed up more runs in April than Iwakuma has for the entire season.

Iwakuma chose to return to Seattle and agreed to a two-year, $14 million contract. He not only has turned himself into the biggest bargain of the offseason, but he is the single best free-agent signing of the winter.

According to Baseball-Reference.com, he is second in all of baseball in Wins Above Replacement (WAR):

Carlos Gomez, MIL: 4.2
Hisashi Iwakuma, SEA: 4.0
Clayton Kershaw, LAD: 3.9
Clay Bucholz, BOS: 3.9
Manny Machado, BAL: 3.8
Adam Wainwright, STL: 3.8
Dustin Pedroia, BOS: 3.7
Troy Tulowitzki, COL: 3.6
Miguel Cabrera, DET: 3.6

Iwakuma is threatening to make his ERA disappear completely. He has not yielded an earned run since the second inning on May 26 against Texas. He stretched his scoreless-inning streak to 24 before an unearned run wrecked it Monday night. He has lowered his ERA to 1.79, which is second best in all of MLB to Clay Buchholz (1.71). Iwakuma maintains the best WHIP in all of baseball (0.82). He is fourth in baseball in innings pitched (95.3), third in batting average against (.190), 12th in strikeouts, third in hits per nine innings (6.04) and sixth in walks per nine (1.32).

His ridiculousness has reached new heights at Safeco Field this season. He is 3-0 with a 0.92 ERA at home. He walked Chris Carter Monday night, which was just the third free pass he has offered up at home. He has fanned 46 and walked just three for an eye-popping 15.33/1 ratio.

Iwakuma boasts the third-best home ERA in the history of the game of baseball for pitchers with at least 15 starts:

Eddie Plank, 1.63
Jim Scott, 1.84
Hisashi Iwakuma, 1.88
Joe Benz, 1.94
Eddie Cicotte, 1.97
Pol Perritt, 1.98
Babe Ruth, 1.98

On May 20, Iwakuma yielded five runs in six innings against Cleveland. If the Cleveland start is removed, only a sparking 1.41 ERA remains.

When peeling back statistical layers to discover what has made Iwakuma so effective this season it is not a surprise to learn that his splitter has been tremendously effective. According to FanGraphs.com, Iwakuma maintains the best split-fingered fastball runs above average per 100 pitches in the game (3.23). The pitch has been so effective that Iwakuma could go ahead and shout that it is coming to the hitter and he would still go fishing in the dirt after it.

The surprise is that he also boasts the best fastball runs above average per 100 pitches in baseball (1.98):

Hisashi Iwakuma, SEA: 1.98
Matt Harvey, NYM: 1.95
Cliff Lee, PHI: 1.94
Mike Minor, ATL: 1.94
Jordan Zimmermann, WAS: 1.88
Clayton Kershaw, LAD: 1.63
Max Scherzer, DET: 1.58
Patrick Corbin, AZ: 1.54
Chris Sale, CWS: 1.48

Iwakuma will take on the Los Angeles Angels in his next start. He has faced them once already this season and hurled six innings without yielding an earned run.

There is a good chance he will give up another earned run this season, but what earthy circumstances could actually bring about such a rare circumstance?