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Norichika Aoki: To worry or not to worry?

The Mariners new left fielder has gotten off to a rotten start. Let's all freak out! Or maybe we shouldn't? I don't know.

Richard Mackson-USA TODAY Sports

After signing Norichika Aoki back in December, Jerry Dipoto lauded his new leadoff hitter's ability to CONTROL THE ZONE.

"Nobody in the big leagues does it any better than Nori Aoki. He draws a fair amount of walks. He doesn’t strike out very much. He’s the hardest player to strike out in baseball, in fact."

Sadly, Aoki has yet to demonstrate this impeccable zone control while wearing a Mariners uniform. One of the things that Dipoto and Scott Servais both seemed to be particularly impressed by was Aoki's ability to avoid striking out (a 7.1 K% between 2013 and 2015, which was ~a third of the league-average). Unfortunately, his K-rate in 2016 is 13.8%more than twice what it was last season! When you factor in his below-average walk rate and his .242 BABIP, you have a whole lot of bad offense. So, yeah. That stinks! But how worried should we be about this slow start?

To try and understand these early season woes, I went and looked at some NUMBERS. Specifically, I checked out Aoki's April splits and compared them with his previous season-long performances. A few things stood out to me, as I've attempted to illustrate in the two plots below.

First, these plots clearly show that Aoki has a track record of not seeing the ball as well at the beginning of the season. A lot of his offensive value comes from not striking out and finding a way to put the ball in play; when he's not doing this exceptionally well, his numbers can get a little ugly (as we've seen so far in 2016). Second, in the past, Aoki has always been able to make the appropriate adjustments and find a way to make better contact as the year goes on. This maybe gives us a reason to believe that Aoki will begin to rebound soon? (Please.)

However, before we get too optimistic, it should be pointed out that Aoki's contact woes have dramatically hindered his overall offensive performance so far in 2016. This didn't really happen in previous seasons. His career wRC+ in the month of April (despite his historic early-season contact ~struggles) is a respectable 101. This season his wRC+ currently sits at 63. That is bad. Looking at his career numbers in the month of April, it's difficult to tell what's going on so far in 2016. His BABIP is a lot lower than it has been in previous Aprils, but his LD/GB/FB rates aren't very far off and neither are his soft/medium/hard hit ball rates. He has become a bit more pull-happy this season, but none of these things are so different that you'd expect them to lead to a 40% reduction in offensive ability. Additionally, Aoki's "speed score" in 2016 is comparable to his career numbers (6.2 vs 5.6), so it doesn't appear as though he's slower this year and missing out on a bunch of infield hits. Taken together, this data seems to suggest that he's likely suffering from a not small amount of bad luck. Again, this indicates that we should consider keeping our distress re: Aoki from getting too out of control. I would recommend engaging in only a moderate amount of hand-wringing.

Coming into this season, Aoki had 2200+ PA of MLB experience where he was a better than average MLB hitter. His career OBP is just north of .350, which is pretty handy in a leadoff hitter (the average leadoff man in '15 had an OBP of .328). He has been a good player, and his track record suggests that he'll fight his way out of this slump sooner rather than later. In fact, if you're looking for a reason to be optimistic that Aoki is starting to see the ball better, I can remind you that he's collected five walks over his last five games (after just one in the first 15 contests). That's good! Alternatively, if you're looking for a reason to adopt a more curmudgeonly outlook, Aoki has gone 6-42 over his last 11 games. That's bad! Aoki has certainly gotten off to a rough start with the Mariners, but it's probably too early to worry about him too much. That being said, if his strikeout rate is still ~14% come the end of May, I would not blame you for doing your best Chicken Little impersonation. Hopefully it does not come to that. Figure it out soon, Nori.

Go M's!