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Thursday, July 26, 2018

J.D. Martinez’s Defense? What The Numbers Really Say

The graphics are goofy; the videos are useful; the conversation is fantastic. A moderate-depth piece from Alex Speier on why some advanced defensive metrics aren’t advanced enough.

“Statcast data has changed the way that internally teams are doing defensive evaluations,” Stern told Martinez. “But to the best of my knowledge, I don’t think very much of that is public, so it hasn’t really changed any of the public-facing numbers that people have access to.”

Martinez had heard similar feedback last year after he was traded from the Tigers to the Diamondbacks. With Detroit, Martinez had graded as well below-average. After his trade, UZR and DRS offered favorable numbers for his work. Martinez recalled a conversation with Arizona head of analytics Mike Fitzgerald in which he discussed the disparity.

“My [UZR] has always been a negative in the outfield,” recounted Martinez. “Then I go to Arizona and my [UZR] is positive. I go, ‘What’s the difference?’ He said, ‘Now we’ve got you positioned right.’ ”

villageidiom Posted: July 26, 2018 at 03:37 PM | 10 comment(s) Login to Bookmark
  Tags: advanced metrics, boston, boston red sox, defense, drs, j.d. martinez, red sox, statcast, uzr

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   1. Jose is an Absurd Force of Nature Posted: July 26, 2018 at 04:40 PM (#5716513)
JDM seems to be pretty good at making plays but is incredibly ungraceful in the process. He's not like Hanley who was always a question if he would actually catch the ball, if JD can get there he seems like a good bet to catch it, he just doesn't seem to be very good at getting there.
   2. Walt Davis Posted: July 26, 2018 at 06:03 PM (#5716546)
I'll give a read later. Did JDM believe he was doing better in AZ? Did he notice he was being positioned differently?

Statcast's catch probability for this year puts him at -4 (compared to an average OF, not LF) this year in very few innings. But the numbers are really weird with a high number of very tough plays (relative to innings), which he makes at a decent rate, while he stinks on high probability balls. Is statcast not properly accounting for the monster?

He was at -6 last year and -9 the year before, playing RF. It doesn't split catches by team for last year but it does positioning. In Detroit RF, he was positioned at an average depth of 292 feet and an angle of 27 degrees; in AZ it was 293 feet and an angle of 26 degrees. The year before in Det it had been 290/26 and this year in Bos it's been 284/27. It doesn't capture variation in positioning which is what we'd want but I suspect the AZ guy was just tooting his own horn.
   3. cardsfanboy Posted: July 26, 2018 at 06:16 PM (#5716550)
I'll give a read later. Did JDM believe he was doing better in AZ? Did he notice he was being positioned differently?


Yes the article talked about that,

With Detroit, Martinez had graded as well below-average. After his trade, UZR and DRS offered favorable numbers for his work. Martinez recalled a conversation with Arizona head of analytics Mike Fitzgerald in which he discussed the disparity.

“My [UZR] has always been a negative in the outfield,” recounted Martinez. “Then I go to Arizona and my [UZR] is positive. I go, ‘What’s the difference?’ He said, ‘Now we’ve got you positioned right.’ ”


Still this article somewhat reads like an advertisement for TruMedia
   4. Foghorn Leghorn Posted: July 26, 2018 at 11:00 PM (#5716659)
For starters -6 isn't "well below average". It's just below average. My system, based on STATS ZR data, has JD at -4 in 2016 *all arm*, so dead average in the field, and likewise for 2017 - dead average in the field.

So maybe it is those stats?
   5. Cooper Nielson Posted: July 27, 2018 at 04:00 AM (#5716674)
It's interesting that they focus almost exclusively on 2016-2017, when in 2015 he graded out as "above average" by the advanced stats and was actually a Gold Glove finalist, for whatever that's worth.

I think that's a good reminder that fielders, like hitters, have "good years" and "bad years," and with the relatively low number of non-routine chances that outfielders get each year, a handful of lucky/unlucky/flukish plays can make a disproportionate impact on sabermetric perception.

I saw a lot of J.D. when he was in Detroit, and my non-expert opinion of him was that, when healthy, he was slightly below average, with a good arm and below-average but not abysmal range. He made his share of nice catches. He's definitely not a guy that needs to be stashed at DH.
   6. Walt Davis Posted: July 29, 2018 at 03:25 AM (#5717593)
For starters -6 isn't "well below average".

But, due to injury, he wasn't a "starter." That -6 Rfield in Det in 2017 was in 440 innings or -16 on a pro-rated full-season basis, well below-average. That was the year after Rfield gave him a -22 (-25 pro-rated). TZ was more kind in both years but did peg 2016 as a -15 which is well below-average and around -16 for a full season across 2016-17 (Det only). Now the year before that, Rfield and TZ both had him positive; the year before that, Rfield put him average while TZ had him negative. And both have him around average this year and for his time in AZ. Quite possibly the injuries in 2016 and early 2017 explain the crappy 1500 innings sitting in the middle of about 3000 innings of pretty average defense.
   7. Sunday silence Posted: July 29, 2018 at 02:05 PM (#5717662)
...with the relatively low number of non-routine chances that outfielders get each year, a handful of lucky/unlucky/flukish plays can make a disproportionate impact on sabermetric perception.


But that almost never happens at least not with players who play at least half a season at one position. YOu rarely find more than a difference of 0.2 in range factor/game on a season by season basis. WHen you do find a drastic drop off it is almost always a sign of age and the following seasons will reflect that. Almost all drop offs in range happen around age 29-30. There's plenty of examples that dont really show any sort of fluke pattern once you've played like 70 or 80 games.

Where you might find something is in discretionary chances, like where Richie Ashburn's range seems a bit swollen; but even then I dont think those would account for more than 0.1/game in range factor .

YOu guys are constantly bringing up stuff that sounds right; but there's no real data out there to support these suppositions. I am working on a compilation of 1960s and 50s, CFers and how consistent their numbers are as a follow on to the thread we had on this a few weeks ago. I dont really crunch numbers with equations and such just back of the envelope calculations
   8. Sunday silence Posted: July 29, 2018 at 02:44 PM (#5717671)
My system, based on STATS ZR data, has JD at -4 in 2016 *all arm* so dead average in the field....




Can you explain what this means? I mean there are million ways to interpret this. Does it mean all the negatives relate to his arm? Or that all the positives relate to his arm? How do we get this all back to "average in the field"? He's average in the field but -4 on his arm?
   9. Sunday silence Posted: July 29, 2018 at 03:08 PM (#5717674)
Getting back to Martinez, looking at his numbers quickly a couple of pts;

2015 seems very different from the '16-'17 years I would certainly avoid lumping those numbers together or using 2015 as some sort of comparison. He seems to have some sort of drop off after 2015.

His range seems average maybe even above. THe stat cast video as him hitting 28ft/sec which is good for anybody I guess Billy Hamilton and maybe a couple other guys can hit 29 but 28 is quite good. In fact as forghorn states the issue seems to be entirely with his arm.

His assists seem well below avg in 16 and 17. So maybe 3-4 runs there. His hold numbers are quite bad. Quick calculations indicate he was holding 9% less runners from taking the extra base Extrapolated out for a full season, you can argue that's 2.5 runs right there.

His arm seems to get better this year, but playing Fenway that has to introduce a huge distortion in such numbers. I dont know how else to quantify it. If you were to play in a band box with say a wall 20 feet behind you and the infield 20 feet in front of you, there's almost nothing that could be said about your fielding numbers. well ok, make it a little bit bigger but you still get the point. A smaller field to cover is just going to minimize your chances and obfuscate what you are doing

Plus he's only played 28 games in RF so there are huge sample size issues here.

BIS has him 2 runs down on the season and extrapolates it to 12 for a full season, not sure where they (Not BIS but whomever suggested it; JD or his manager or the writer) get the idea he's improved. His arm is probably as weak as it ever was and the smaller park is maybe diminishing this effect. I dont know how many games he's played in Fenway to be honest.
   10. villageidiom Posted: July 29, 2018 at 03:32 PM (#5717681)
Does it mean all the negatives relate to his arm? Or that all the positives relate to his arm? How do we get this all back to "average in the field"? He's average in the field but -4 on his arm?
Yes. No. See the next answer. Yes.

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