Iwakuma, 31, went 9-5 with 2 saves and a 3.16 ERA overall in 30 appearances, including 8-4, 2.65 ERA in 16 starts. His ERA as a starter set a rookie club record, bettering the previous mark of 2.67 by Felix Hernandez in 2005. Amongst AL pitchers with at least 100.0 IP, he ranked 7th with a 3.16 ERA (44 ER, 125.1 IP), and had the 3rd-lowest ERA by an AL starter with a minimum of 15 starts.
“Hisashi did a very nice job for us at the end of last season as a starting pitcher and we are happy that we have come to a mutual agreement. We look forward to his veteran presence and to his contributions for the next few seasons,” said Zduriencik.
Iwakuma finished the season going 6-2, 1.83 ERA (11 ER, 54.0 IP) with 43 strikeouts over his last 9 starts, posting the 2nd-best ERA by an AL starter during that stretch (Max Scherzer, DET, 1.72 ERA). Iwakuma also set the Mariners rookie record with 13 strikeouts in first MLB win as a starter July 30 vs. Toronto.
"Kuma really helped solidify our rotation in the second half of the season," said manager Eric Wedge. "He is a competitor on the mound and did a great job for us. He got stronger with each start during the season and gained confidence. I am looking forward to seeing him on the field ready to work when we start spring training in Peoria."
Prior to joining the Mariners last season, Iwakuma compiled a 107-69 record in 226 career games with Kintetsu (2001-04) and Rakuten (2005-2011) in the Japan League. He was named the 2008 Pacific League MVP and winner of the Eiji Sawamura Award (Cy Young equivalent) after going 21-4 with a 1.87 ERA (42 ER, 201.2 IP) in 28 starts.
The right-hander was a two-time selection for the Best Nine Award (2004, 2008) and was a two-time NPB All-Star (2004, 2008). Iwakuma also starred for Japan in the 2004 Athens Summer Olympics (Bronze Medal) and the 2009 World Baseball Classic (Gold Medal).