Oct 1, 2016; Seattle, WA, USA; Seattle Mariners starting pitcher Hisashi Iwakuma (18) and catcher Mike Zunino (3) react after gaving up four runs to the Oakland Athletics during the third inning at Safeco Field. Mandatory Credit: Jennifer Buchanan-USA TODAY Sports

For Seattle Mariners starter Hisashi Iwakuma, 2017 hasn’t been kind. The veteran of the staff has put up disappointing numbers, so what’s behind his rough start?

It’s always seemed as if age was just a number for 36-year-old Hisashi Iwakuma. As the number grew, it seemed he’d found new ways to outsmart the inevitable task of growing old. However, four starts into 2017, it appears Father Time may be catching up with him after all.

When looking at the stat sheet, his 5.31 ERA isn’t the only thing that stands out. That number is the result of a few things.

Behind Iwakuma’s slow start looks to be a lack of control. After averaging just under 35 walks per season through his first five years in the major leagues, he has already allowed 10 in 2017. In three of the four games he’s started he has walked at least three batters.

In addition to the solid walk numbers over his career, Iwakuma has allowed a relatively low amount of home runs, too. In his first five seasons in MLB, the native of Japan allowed an average of 21 round trippers a year. In 20.1 innings this year, he’s given up six, a home run rate of 2.7 HR/9 in the early going.

While these numbers aren’t awful, they are the continuation of a worrisome yet inevitable trend for pitchers of his age; a decline.

Here is a look at Iwakuma’s ERA since the 2014 season, per baseball-reference.com.

2014 – 3.52

2015 – 3.54

2016 – 4.12

His ERA isn’t the only thing that has risen, as his WHIP since 2014 has increased by .32.

Before he even came to the states, he logged 1,541 innings in the Nippon Professional League of Japan. In his time in the majors, Iwakuma has amassed 873 innings, coming out to a total of 2,414 innings over a 16-year career.

If he had spent his entire career in the United States, he’d be fifth on the active innings pitched list.

So, should we be convinced that Iwakuma is falling victim to age? Well, maybe.

There’s enough reason to think that Iwakuma can rebound to post better numbers as the year goes on. After all, he has only made four starts.

Part of the reason his ERA is so inflated is due to the fact that he gave up six earned runs in a start against the Texas Rangers. In his other three, he allowed three or less runs each time.

Even if he does rebound, which is likely, it’s clear to see that Iwakuma’s time in the majors is dwindling. His arm has a lot of mileage on it, but also, a fair share of the Mariners playoff hopes.