I Think I May Have Found Something ‘Wrong’ with Jake Arrieta

The title sounds like a pretty stupid premise when it refers to a guy who’s 9-1 with a 1.80 ERA, has a Cy Young trophy on his mantle, and rocks the kind of thick, lustrous beard that turns hipsters and lumberjacks alike green with envy. Still, despite all the accolades and the great performances, something has seemed a little…off(?) when I have watched him lately. I have no doubt that a lot of that, maybe all of it, comes from the guy just being so historically good for so long.

Before I get started, I want to make sure to walk back the whole click-bait-y title and reassure you that I’m not trying to present some sort of Chicken Little warning here. I am, however, a little concerned with a couple things I’m seeing from Arrieta lately.

The first is the increase in walks, which seemed to start with, of all games, that no-hitter in Cincy. Arrieta was admittedly sloppy and was having trouble locating, which led to four more walks than the Reds had hits on the evening. But from that game on, the ace has averaged 3.72 walks per game over his last nine starts, which stands in stark contrast to the 2.01 walks he had averaged in the previous 61 starts.

Arrieta is also striking out one more batter per 9 innings (10.40 vs. 9.34) in that period, though it’s not enough to account for the additional walks. His K/BB ratio has dropped from 4.65 to 2.79, which is still higher than the MLB average of 2.54, yet is getting dangerously close to pedestrian. Acceptable for most guys, sure, but this is Jake Freaking Arrieta we’re talking about. He’s not supposed to look mortal.

And while the overall line might not reveal him as anything less than a demigod, Arrieta hasn’t been quite as consistent of late. Heading into his start against Milwaukee on April 28, he had gone at least 6 innings in 24 consecutive starts. He lasted only 5 that game and has not pitched into the 6th in three of seven starts since, essentially tossing a shorter stints every other outing.

That makes a lot of sense when you think about it, since a guy who’s walking and striking out a lot of batters is generally going to throw more pitches. That, in turn, leads to shorter outings. In an effort to see if I could find a reason for these issues, I looked first to heat maps of the samples in question. The first map below shows Arrieta’s pitch location over his last nine starts and the next is indicative of the previous 61.

I know it may not be easy to compare the two, particularly if you’re viewing on a mobile screen, so I’ll give you some time to scroll back and forth and we’ll reconvene after the second one.



At first glance the differences might not seem too stark, but you can pick up some pretty clear shifts if you look closely. Arrieta is working much more heavily just below the zone, hitting the lower fifth of the map at just over 35 percent of late as opposed to just under 31 percent previously. If we focus on the lower third of the zone and the three regions just below, the differences are even more obvious. From 2014 through his first couple starts this season, Arrieta located only 33.26 percent of his pitches there. Over the last several starts, however, he’s upped that to 39.92 percent. He’s not just working down in the zone though, he’s shifted a little more over the plate.

As you view the charts, the column to the right represents inside pitches to lefties and, naturally, outside to righties. Arrieta located 17.18 percent of his pitches there from 2014 to early 2016, but only 12.88 percent of late. Like I said, nothing drastic. Not necessarily concerning, either, just different. Okay, so that’s the how. What about the why?

Admittedly, I’m in pretty deep waters when it comes to analyzing a pitcher’s mechanics or trying to recognize any differences in his delivery or approach. Absent a scout’s eye, I went digging around in the haystack of numbers over at Brooks Baseball to see if there was a compass needle to provide me with a true north. The first thing I noticed was the difference in Arrieta’s pitch mix, particularly his primary offerings of the fastball and slider.

While Arrieta went the to the heater for only about 50 percent of his pitches previously, he’s leaned on it for 62.5 percent of his offerings over the last nine starts. Conversely, the slider/cutter has gone from 28.6 to 19.5 percent usage in that time. The curve and change have varied a bit too, though not enough to raise an eyebrow given the sample in question and the fact that they’re secondary or tertiary pitches. I must say, however, that the curve seems to have been particularly nasty of late.

Pitching, particularly at the highest level, is all about feel. Even Jake Arrieta can’t just walk out to the bump and start snapping off sick breaking pitches with the perfect grip each and every time. Sometimes you just can’t get the grip right and the feel just isn’t there. It would appear that’s been the case with his devastatingly effective slider, so I went looking for some data to see if anything had changed in terms of the way Arrieta is throwing.

The velocity on his pitches has remained pretty static, though the data on the slutter gets a little squirelly when you consider how different pitch-tracking services categorize the pitch. Suffice to say there doesn’t seem to be sufficient variance in velo to provide a rabbit trail to follow. The same can be said for horizontal and vertical movement and also horizontal release point, all of which have stayed more or less the same over the last couple seasons. Sure, those things have varied, but nothing jumps out.

Until, that is, I looked at vertical release point. Take a look at this:


And now let’s look at those same stats normalized over the course of full seasons, just to get a clearer picture of what we’re seeing.


Okay, so that’s something. It does appear from the first of these charts that Arrieta’s release point was down in his last start, but you can’t base too many conclusions on a single outing. Again, just treading water here, but I’m thinking we may be on to something. A noted cross-body thrower who takes a while to get warmed up, it’s entirely possible that raising his arm slot has cost Arrieta a bit of control here in 2016.

In order to see exactly how that could be affecting him, let’s do a little (overly simplified) visualization exercise using the heat maps from earlier. Those are from the catcher’s POV, so imagine you are Miggy Montero and you’re staring through that second map floating in front of you as you look at your pitcher. Imagine following his pitches as they leave his hand at a certain point and then see as they light up the iridescent squares of the map when they pass through.

Now imagine that your pitcher has changed his arm angle and that he’s releasing the ball just slightly higher than before, only two inches or so, and that he’s letting go of the slider in particular just a fraction of an inch closer to his body. Can you see how those pitches might light up the squares of your heat map with different frequency? Great, now stop daydreaming about the damn heat maps and block that curve in the dirt!

Alright, that was kinda fun, but how serious is this issue? Well, over the course of those 61 starts I’ve been referencing, Arrieta had a 2.03 ERA with a 2.34 FIP and allowed only 0.38 home runs per 9 innings. In the most recent nine starts, he’s had a 2.02 ERA with a 2.38 FIP and has allowed only 0.17 home runs per 9 innings. His average game score in both samples was 65. Pretty much exactly the same stats with fewer home runs. So does this mean my worries have been allayed?

Well, yes and no. While the aggregate results are almost identical, it’s the lack of consistency that continues to nag at the back of my mind. The velocity is still there and the stuff is just as nasty, but working a little lower in the zone is having an impact. Even though MLB hasn’t instituted the new strike zone rules, you can imagine umpires being a little less forgiving down there, which leads to more pitches, which leads to fewer innings. Most any other pitcher would be ecstatic to have stats like those Arrieta has posted recently, but we’re not talking about most any other pitcher.

That cuts both ways, though, and there’s some really good news in all this as a result.

Remember how Arrieta closed out the 2015 season on an unprecedented run that saw him beat out Clayton Kershaw and Zack Greinke for the Cy Young? Yeah, he wasn’t even named to the All-Star team based on his first-half performance. What I’m saying is that Arrieta’s already starting from a better spot and that he’s got plenty of time to dial in the mechanics and tighten that control up a bit as the season goes on.

What do you think, though? Am I crazy for wondering whether there’s something amiss, or do you think Arrieta might want to address these flaws (minor though they may be)? Or do you think I’m crazy and Arrieta could still tighten up?

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