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In the offseason prior to the 2012 season, Yu Darvish was one of the most sought after pitchers on the market. The Rangers paid over $51 million for the right to negotiate with him, and gave him a 6 year, $56 million contract. Meanwhile, another Japanese starter, Hisashi Iwakuma, signed with the Mariners for $1.5 million on a one year deal.
In his brief two year American career thus far, Iwakuma has always been one of the most underrated, unknown, great pitchers in the game. He is second in all of baseball with a 1.79 ERA, yet nobody even considers him as his team’s best pitcher. After quietly (as always) putting up a very productive rookie season last year, Iwakuma is now dominating hitters while, once again, not getting much recognition for it.
Clearly, Iwakuma has improved markedly since last year, so let’s take a look at why he has been so much better. Looking at his individual pitches, the biggest improvements lie within his fastball and his curveball.
Iwakuma’s splitter has been very dominant this year, but it was last year as well. The biggest improvements this year seem to be on his fastball and curveball. He only throws his curveball on 6% of his pitches, so let’s look at his fastball first.
Iwakuma’s fastball has never had overpowering velocity. However, he is getting more chases on fastballs outside the strike zone and more swings and misses on the pitch this year compared to last.
They key to his fastball improvement has been keeping it off the middle of the plate. He has used it to come inside on hitters more often while keeping it out of the middle.
Looking at the past two seasons, we can see that Iwakuma’s fastball is at its best when it’s thrown inside. The pitch has improved on all parts of the plate, but has always been best when thrown inside.
Let’s switch gears to his curveball, which although is not used as often, has also shown drastic improvement. While he has been using his fastball inside, the difference in the curveball lies in keeping it down.
He has not thrown enough curveballs that have been hit so far this year, but looking at last season, his curveball was unsurprisingly at its best when thrown low.
Overall, Hisashi Iwakuma has a lower batting average against, lower slugging against, a higher strikeout rate, and a lower walk rate this year compared to 2012; surely a recipe for success. His fastball has improved dramatically, and he is using it to jam hitters inside. He is also keeping his curveball down, where it is at its best. He is putting it all together to become baseball’s least known ace.