Going Deep: The Greatest Choo-dunit of All Time!

Gumshoe, Sleuth, Flatfoot, Sherlock. These are all classic nicknames for detectives solving the toughest mysteries throughout history and literature. I have one more I’d like to add to the list: Fantasy Baseball Writer. I know, I know, that is a tasty bit of hubris — bear with me. I love mysteries and throughout my entire life I’ve pretty much devoured any puzzle, riddle, or whodunit I can get my hands on: from Encyclopedia Brown and The Hardy Boys as a kid, to Agatha Christie and Raymond Chandler in college, to the Michael Connelly novel I just put down before I started writing this. I love being given the end result of something (a crime, a baseball season, an algebraic equation, whatever) and trying to suss out the bits and pieces to figure out what caused that event or end result. I think this is what draws me to write about fantasy baseball, and really baseball as a whole. In an abstract way, whenever we look at what is going on with a player, there is little difference between our processes and the methods Holmes and Watson used when they stalked around crime scenes. That methodology is called deductive reasoning, which is the process of starting with the conclusion and working your way backward through the evidence to lead you to the “why?” of your mystery. We do this every single day in fantasy baseball, especially in the Going Deep department here at Pitcher List (we need branded deerstalker caps so very badly).

This week, I found myself unexpectedly confronted by one of the more difficult enigmas I’ve run into so far in this young fantasy season: What do we make of Shin-Soo Choo hitting like he wants to win the AL MVP this year? We’re talking about a guy at 36 years old that is still sitting on a lot of waiver wires; Yahoo has his ownership percentage at 62%, while he is owned in 76% of CBS leagues, 62.7% of ESPN Leagues, and he’s the 22nd ranked outfielder according to ESPN’s Player Rater. Is his season legit? Will his success continue? It honestly could go a lot of different ways, but I think the key to solving this mystery (believe me it is a much more complex riddle than it appears on the surface) is to use deductive reasoning. Sherlock Holmes style, we’ll see if, my dear Watson (Tony Watson naturally!), we can find what has led to Choo’s success this year and see if it is really as unprecedented as we think it is.

 

First, we begin with the end: Choo’s 2019 season so far. He has had an incredible year leading off for the Rangers. Here are his numbers as of today:

 

AVG	PA	HR	R	RBI	SB	OBP	OPS	wRC+	BB%	K%
.324	127	4	21	13	2	.409	.568	156	11.0%	20.5%

 

Wheee doggie, that’s a fantastic production.  Just to put things in perspective, if you extrapolate the counting stats over an entire season for Choo (who averages about 650 PA a season or so, barring injury in 2016) this is what his whole season would look like:

 

AVG	PA	HR	R	RBI	SB	OBP	OPS	wRC+	BB%	K%
.324	650	20	107	67	10	.409	.568	156	11.0%	20.5%

 

That’s really great for a 36-year-old you likely picked up off the wire or drafted in the last few rounds. But how legitimate is it? Why, that’s the very mystery we’re trying to solve! Let’s start with everyone’s favorite luck statistic: BABIP! Here is Choo’s 2019 BABIP, along with that of his last three full seasons (his 2016 was cut short by a series of injuries including a fractured forearm):

 

Year	BABIP
2015	.335
2017	.305
2018	.330
2019	.395

 

So it’s obvious that Choo is benefiting from quite a bit of luck and is due for some major regression — but how much? Not quite as much as you would think. Check out his xStats and Statcast numbers for the season.

 

Year	AVG	SLG	wOBA	Launch Angle	Exit Velocity	BBL%
2019 Actual	.322	.568	.413	11.2	92.9	7.3%
2019 Statcast	.302	.518	.393	11.2	92.9	7.3%

 

In reality, within a certain margin for error, the Statcast data pretty thoroughly supports his early success this season. Sure, there’s some luck involved, but we’re still talking about a hitter with an .890 to .910 OPS, and any hitter that puts up a .393 wOBA is an elite one.

Before the season, depth charts predicted a .320 BABIP for Choo; while I think on the surface that is a reasonable prediction, I’m not sure it’s completely right. This leads me to talk about where the real mystery lies underneath the story: Choo’s 2018 season. When you dive into his last season, you find a lot of information that changes the lens through which we view Choo’s 2019 season and hopefully illustrates that his production might not be as far-fetched as it seems. Let’s take a look.

If you’ve read my pieces the last few weeks on interpreting BABIP, you know the very first thing I look for is any change in the player’s swing or stance. A decently thorough search doesn’t reveal any major swing changes coming into 2019, but that’s because the swing change we’re looking for occurred right before the 2018 season; Choo added a modified leg kick as an additional timing mechanism while shifting to a more focused and disciplined approach to the game. Here’s his swing back in 2013 when he hit a walk-off HR off of Craig Kimbrel.

 

 

No leg kick right? Here’s a HR he hit last year.

 

 

The difference is pretty clear. Adding a leg kick would likely help with timing, bat speed, and keeping up with fastballs as Choo aged into his 35th year of life. It took about a month to lock it in, but once Choo did he took off like gangbusters. Here are his numbers from May 1st to the All-Star game (July 17th):

 

PA	AVG	OBP	OPS	wRC+	wOBA	R	RBI	BB%	K%	ISO
285	.323	.447	.999	168	.429	36	31	17.5%	22.1	.228

 

Now that’s a hot streak. In fact, those numbers should look pretty familiar. Here are those numbers up against his 2019 numbers.

 

Year	PA	AVG	OBP	OPS	wRC+	wOBA	R	RBI	BB%	K%	ISO
2018 1st Half	285	.323	.447	.999	168	.429	36	31	17.5%	22.1	.228
2019	127	.324	.409	.977	156	.413	21	13	11.0%	20.5%	.243

 

Obviously, we’re talking about a sample nearly half the size of last year’s hot streak, but it’s truly remarkable how much these two hot streaks match up. While this is really interesting, we first need to talk about the second half of 2018. Pretty much from the All-Star game on Choo’s season completely fell apart.

 

PA	AVG	OBP	OPS	wRC+	wOBA	R	RBI	BB%	K%	ISO
254	.223	.339	.673	84	.305	31	20	12.6%	25.6%	.112

 

Yikes. What happened? This is where we find the real mystery we have to solve. If we figure out what happened in the second half of 2018, we can likely answer the question of how legitimate his 2019 numbers are. The first thing I look for is anything deviation from the Choo’s numbers from the last few full years, starting with his batted ball data and plate discipline numbers, and then I do the same with his Statcast data. Here’s the batted ball data:

 

Year	LD%	GB%	FB%	HR/FB%	Pull%	Center%	Oppo%
2015	20.7%	50.9%	28.5%	18.8%	44.1%	34.2%	21.7%
2017	25.5%	48.8%	26.2%	20.4%	42.8%	33.7%	23.4%
2018 1st Half	22.6%	45.9%	31.5%	22.4%	40.2%	34.0%	25.9%
2018 2nd Half	20.4%	57.8%	21.8%	9.4%	34.0%	37.2%	28.4%
2019	20.2%	45.2%	34.2%	13.8%	38.8%	34.1%	27.1%

 

Once again, note the similarities between that 2018 first half and his 2019 profile. With that being said, that 2018 second half sure sticks out like a sore thumb when compared to the last few years, especially the GB%, HR/FB%, and Pull%. It’s clear right away something was up. Given that huge spike in GB% and dip in power, I tend to lean towards an injury of some sorts. A quick Google search confirms my suspicions: Starting on June 30th, roughly 17 days before the second half began, Choo began suffering from a sore quad. Choo apparently requested an MRI (never a great sign) and, while it came up negative, it bothered him enough to hold him out of a couple of games leading into the All-Star break. The Athletic’s beat reporter for the Rangers, Levi Weaver, called it a mild quad strain and mentioned that, while it wasn’t severe enough to put him on the IL, it hurt enough that he wouldn’t play the field anytime soon. If it was affecting him that much, it follows that Choo had to be feeling that injury at the plate. We see a follow-up report on July 11th that indicates that Choo had missed two of the last three games due to the quad injury. After that, I was unable to find any report or mention of the quad injury. Did the injury linger beyond that? There is no way to know for sure. What we can do is look for the typical evidence that tends to indicate an injury and see if we can draw a reasonable conclusion from there. The huge jump in GB% and drop in both HR/FB% and Pull% make up our first big clue.

For our second clue, let’s take a look at Choo’s Statcast data and see if anything jumps out at us. You may remember my xEPH (Expected Elite Power Hits) statistic from an article I wrote back in the preseason comparing Ji-Man Choi to Michael Conforto. The goal is to quantify what percentage of pitches a hitter sees are hit for an xISO of .200 or better. For our purposes, I thought it would be a nice compliment to xSLG, since it can provide some context to the kind of hits the player is putting together to get to that xSLG. Here are his Statcast numbers by month in 2018:

 

Month	xBA	xwOBA	xSLG	Exit Velocity	Launch Angle	BBL%	HardHit%	xEPH%
April	.246	.341	.471	89.7	6	12.4%	42.7%	4.5%
May	.267	.376	.454	90.6	7	8.6%	45.7%	3.5%
June	.275	.405	.548	89.1	10	14.1%	40.8%	4.5%
July	.258	.405	.579	89.4	6	20.3%	44.1%	4.2%
August	.237	.328	.393	86.3	1	7.6%	36.4%	3.8%
Sept	.218	.301	.310	88.6	7	1.9%	26.9%	2.9%

 

It’s remarkable. We see the numbers grow steadily month to month, as Choo likely gets more settled into the new swing and really starts squaring up the ball. Then we hit August (11 days after the All-Star Game) and it falls apart like a cheap suit. I would say it was likely the result of impending regression; I can’t think of anything other than an injury that makes numbers plummet quite like that. I included the xStats so that they could perhaps provide a frame of reference for the quality of contact Choo was making. The most telling stats though are his Launch Angle, Exit Velocity, and Hard Hit%. Hitting the ball hard and for power is all about your legs. Even the slightest injury to your legs can sap you of your ability to drive your hips and swing the bat with authority. Much like how we can predict pitcher injury by looking at Statcast data such as spin rate or release point, a drastic drop in Exit Velocity, Launch Angle, and Hard Hit% can indicate a potential injury in a hitter, especially when it is as drastic as the above numbers show.

One last piece of evidence that I want to throw out there is Choo’s playing time, in particular how often he played in the field. In the first half of 2018, Choo DH’d roughly 69% of the time. In the second half, Adrian Beltre was fighting through some injuries and had to spend more time at DH, leading Choo to spend more time in the outfield. In the 56 games he played during the second half, Choo only got to DH 43% of the time. At 35, it couldn’t have been easy to recover from and play through a strained quad while having to suddenly playing in the field more.  We can certainly see something was sapping Choo of his ability to drive the ball in the second half, and it seems likely it was a combination of a leg injury and playing the field more often. It’s also worth noting that this combination of factors would likely help explain his gradual decline, as the wear and tear added up on top of the injury. Add in the massive increase in GB% and Pull% to go along with all flashing signs present in the Statcast data and it seems pretty clear what is the culprit here. At least I’m hoping we’ve found one a jury of my peers would be willing to convict.

I can’t prove definitively that Choo’s quad strain lingered throughout the entire second half, but there is a lot of evidence that backs up my theory. At some point, Occam’s Razor kicks in and we have to go with the most likely explanation. So after all this sleuthing, why is this relevant? If you remember from earlier when we compared Choo’s year-to-year numbers, the underlying numbers from May, June, and most of July 2018 lined up almost perfectly with his 2019 stats. For a second, let’s operate under the assumption that the quad injury is what derailed Choo’s season in the second half and those numbers should be viewed separately. This gives us a roughly 412 PA sample size over the last year (plus one month), with a healthy Choo putting up elite production after adding the modified leg kick. That’s just barely under two thirds of a full season, which is pretty significant.

So now that we have uncovered the likely quad-related villain of our story and established statistical evidence that the new leg kick really did allow Choo to breathe new life into his career, what should we expect from the rest of his season? If we’re willing to assume season-long good health (which I will fully admit isn’t a sure thing given Choo’s age, extensive injury history, and willingness to play through injuries), we should still expect some regression — he can’t possibly sustain a .395 BABIP. His xStats and BABIP history tend to suggest that he should be hitting closer to a .330 or .340 BABIP right now, especially when you consider that he had a .350 BABIP for that elite first half last year. If you were to adjust his numbers to a .335 BABIP (I’m splitting the difference so sue me) you end up with a .273/.380/.861 hitter who will likely hit somewhere between 20 and 25 HRs while batting leadoff in a great hitter’s park for a Rangers offense that is currently fourth in the league in runs scored and 11th in wRC+. If you fully believe his new approach will sustain his xStats, then we’re talking about a .302/.408/.916 hitter batting leadoff in that same ballpark and same lineup.  For what’s it worth, I estimate it’ll fall somewhere in between, thanks to a combination of regression and the suspicion that Choo will likely get at least somewhat dinged up at some point and time. I think it would be reasonable to expect somewhere between a .275 and .285 AVG with those 20-25 HR, 85-90 R, with solid enough RBI, and 5-7 SB. He was already must-own in OBP and points leagues, but this could push him closer to near-elite production in those formats. Not too shabby for a player most of us picked up off the wire.

To close things out, I want to stress a few things. While I am encouraged by what we’ve seen from Choo over the last year and a half, he is 36 and staying healthy will always be a challenge for him — being especially susceptible to wear and tear and hidden injuries like last year. If you have someone willing to pay the price for his current production, I’d be very hard pressed to not sell high while I can. With that being said, given health he can be a complete game changer for your offense. If you believe in Choo and plan to hold on to him (I am doing this in a few of my leagues) then I would highly suggest checking in once a week or so on those underlying numbers that we have talked about here. Check in on his launch angle and exit velocity, his Pull% and GB%, and his HR/FB%. If you see them start to trend downhill over a month or so, you know to sell. At the very least, I would set a threshold for those numbers; once they’re below your threshold, you are going to cut bait and start shopping him. Choo is showing some big-time production this season and there is a good reason to think he might keep up most of it all season long. Rostering players like Choo requires having a plan in place, but when armed with one, he could possibly be the kind of player that helps you win your league. Mystery Solved. Case Closed!

(Photo by Leslie Plaza Johnson/Icon Sportswire)