Archive for MASH

Fresh for the Playoffs – Pre-Playoff Fatigue Units

Fatigue units attempt to physiologically represent the workloads pitchers face. This includes velocity, days of rest, pitches per inning, and even the pace they pitch. Pitchers with extreme workloads were 2.7x more likely to have Tommy John surgery when compared to pitchers with moderate workloads. Who has worked the hardest in 2017?

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Mid Season Pitcher Workloads

At the midway point of the season, it’s always interesting to see how teams are utilizing their pitching staffs. I’ve been examining workloads through the metric I created, called Fatigue Units. This metric accounts for days between appearances, stress during pitching, and time between pitches – you can read more about it here. TLDR; Fatigue Units appear to be a more accurate indicator of “overworked” pitchers than pitches, or innings pitched.

To start off – what does the midway point indicate about a pitcher’s workload? It doesn’t necessarily indicate what the workload will be by season’s end, but it does say that the pitcher has worked hard in the first half. It definitely says that the team has trusted that pitcher, and, that pitcher is very good. Here’s what the halfway point workloads looked like in 2016.

2016 All Star Break Workloads
Rank Name Fatigue Units Average Days Between Games SD of Days Between Games Appearances Inning Appearances 5 or More Days Rest 2 – 4 Days Rest 1 Day Rest Pitch Count
1 Nate Jones 14.46 2.42 1.93 49 63 8 21 20 685
2 Travis Wood 14.15 2.34 1.48 51 64 6 27 18 693
3 Chris Sale 13.85 6.05 1.47 20 144 20 0 0 2117
4 David Phelps 13.48 2.37 1.32 50 61 6 29 15 923
5 Max Scherzer 13.44 5.52 0.87 22 150 22 0 0 2327
6 Seung Hwan Oh 13.36 2.27 1.13 52 57 4 33 15 895
7 Zach Duke 13.14 2.23 1.26 53 62 5 31 17 615
8 Dellin Betances 12.94 2.33 1.48 49 56 5 30 14 817
9 Ryan Pressly 12.68 2.35 1.32 50 63 3 33 14 843
10 John Lackey 12.39 5.60 0.88 21 141 21 0 0 2099
11 Chris Archer 12.22 5.43 0.60 22 135 22 0 0 2254
12 David Hernandez 12.04 2.50 1.28 47 55 5 30 12 832
13 Johnny Cueto 12.04 5.42 1.38 21 151 21 0 0 2226
14 Madison Bumgarner 12.03 5.43 0.60 22 154 22 0 0 2331
15 Bud Norris 12.02 4.11 1.76 28 109 15 12 1 1693

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PitchFX Forensics: Julio Urias and Anterior Shoulder Capsule Tears

The Dodgers Julio Urias is done for the year, and probably most of next season, with a torn Anterior Capsule – a devastating shoulder injury. The anterior capsule is a combination of ligaments which provide stability to the shoulder. Have you ever heard someone state that they had “a frozen shoulder”? Well, frozen shoulders (or, adhesive capsulitis), is impingement of that same capsule, and it results in huge range of motion loss, and incredible discomfort. You can imagine how damage to that structure would be catastrophic to a pitcher.

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Are the Dodgers playing DL games?

On the last MASH report, I discussed Alex Wood’s S/C joint sprain, and many of the commenters claimed it was #FAKENEWS.

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In Game Velocity Changes – When Fatigue Attacks

Velocity changes between seasons, or even games, are well reported on thanks to Jeff Zimmerman’s velocity tracking document.

Velocity is very important to the success of pitchers – as I’ve written about with respect to my Stuff metric, and as highlighted in this great article by Mike Fast from 2010, every little bit of velocity matters. Within pitchers – those who lose velocity become shells of their former selves – like Eno Sarris wrote about Matt Harvey before this season started. While a Velocity drop between games is an indicator that someone might be hurt, a velocity drop within a game might indicate that a pitcher is becoming fatigue – a big sign of possible future injury.

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MASH Report: Alex Wood, Danny Duffy, and Mike Trout

Attempting to write a MASH report is like being asked to replicate the Mona Lisa. I can’t hope to do any better than what the legendary Jeff Zimmerman has done in the past – but let me try to put my own spin on things.

Alex Wood

There are a few things that come to mind when you hear about a shoulder injury in a pitcher. The first is usually the rotator cuff strain. If your pitcher was super in to dirt bikes – it might be a separated collar bone. Worse off – you might hear about a labral tear in the shoulder. However, it’s SUPER rare to hear about an SC joint strain.

To orient you to a bit of anatomy, the collar bone links your sternum to your shoulder blade via two joints – the acromioclavicular joint, and the strenoclavicular joint. If you’ve heard about someone landing hard and suffering an AC sprain – that’s a sprain of the end of the collar bone closest to the shoulder joint. The other end, and what Alex Wood is dealing with, is the SC joint.

I’ve checked with Baseball Injury Consultants, and did some rather extensive Googling, and I can’t seem to find any other cases of SC joint inflammation in pitchers. Internet, I’m sure you’re about to prove me wrong. I would expect this to be the type of injury that makes pitching very painful, but once the inflammation dies down, he’ll be no worse for the wear.

Danny Duffy

The Royals Danny Duffy has been very solid this season, pitching to the tune of a 3.54 ERA, and a 3.43 FIP. On Sunday, he went on the DL with an oblique strain that he suffered while covering first base on a grounder. The Royals have publicly stated that he could miss 6-8 weeks – and before I got into my own analysis, I found this great tweet by Shaun Newkirk.

An average of 44 days due to oblique strains is a long time to miss. I dove into the scientific literature on the importance of the obliques during pitching, and you can see why it takes so long for arms to return from this injury.

During the pitching motion, the obliques are at near 100% of their capacity (Watkins et al., 1989). These muscles are hugely responsible for torso rotation – a massively important part of the pitching motion. Without healthy obliques, velocity will fall, and pitchers will lose their effectiveness. Unless the pitcher is 100% healed from this injury, the chances are their performance will suffer.

In particular, the non-dominant side oblique is more active during motion (so for Duffy, this would be his right side). This is responsible for the torsion required to throw hard, but also, to protect the lower back from injury during pitching.

If this is a severe injury, don’t expect Duffy back until he’s completely healthy – and the process could start all over again if he is rushed back for a rehab assignment before he’s completely healthy.

Mike Trout

Having me write about a hitter is like having Roger Ebert write about a Cubs game – if he was a really marginal movie critic. Pitching has been the focus of my writing, but what does science know about the UCL tear that Trout suffered while sliding in to second base on the weekend?

This UCL is a lot less severe than the UCL associated with Tommy John Surgery – however, this ligament serves a very similar role in stabilizing the lateral bending of the thumb (compared to the elbow). This vaglus/varus motion, when in extreme force levels, can lead to a rupture of the ligament.

In the orthopaedic world, a complete tear of the thumb’s ulnar collateral ligament is referred to as a Stener lesion, or “Game Keeper’s Thumb”. Go and Google why it’s called Game Keeper’s thumb, I’ll wait.

Welcome back. Pretty messed up, eh? A review by Ryu et al., in 1995 showed there were very inconsistent results when athletes pursued non-operative treatments of this injury – and that surgical options were preferred for long term success.

This injury is associated with a very weak pitch and painful grip – which would significantly impact Trout’s ability to grasp the bat. For return to play times – the news isn’t great, but it’s not as bad as it could be. In a review by Schroeder & Goldfarb (2015), they advised a 6 to 12 week recovery time, including rehabilitation, from surgery.

For the fantasy baseball player, losing the first overall pick is a huge kick in the groin. Hopefully you can tread water before getting Trout back for September and the playoff run.

I’m going to try and do a bi-weekly MASH report from here on out – if you have any players you’d like to have reported on – hit me up on Twitter: @DrMikeSonne

PITCHf/x Forensics: Shelby Miller

Poor Shelby Miller. After last year’s disastrous debut with the Diamondbacks, Miller was looking forward to getting back to his previous Cardinals and Braves form. The season started well enough – his spring training was filled with reports about his increased velocity, and how well he was pitching.

In my initial calculations of STUFF for the 2017 season – Miller was up from 0.56 in 2017, to 0.84 in 2017. That is a huge increase that shows great promise for turning a career around. But now – the dreaded third opinion from Dr. James Andrews, and the discovery of a strained flexor muscle, and a torn UCL, which could lead to Tommy John Surgery, or at minimum, a year off with rehabilitation.

What risk factors were present that could have lead to Shelby Miller’s UCL tear? Let’s look at the research.

Table 1. Known risk factors for UCL reconstruction from research.

The interesting thing about this analysis – is that the 2016 iteration of Shelby Miller has no risk factors that particularly jump out at you. He’s right in the moderate area for everything, save for pitches per game – but that value is quite comparable to every other starting pitcher, if not lower. At the same time, this is a case of the sum of all parts – a compounding situation where it’s death by 1000 paper cuts.

Miller broke into the league in 2012, and his Stuff has remained relatively stable since. The biggest change in his Stuff has been this season – and, I’ve tried to take into account the change in data by re-normalizing Stuff to only 2017 data, and subtracting 0.4 mph from the fastball velocity.

Figure 2. Shelby Miller fastball velocity and Stuff, 2012 to 2017.

2017 is clearly a change here – the velocity is up significantly, and that’s not really something that happens when someone gets older. There are a lot of variables in play that we can’t quantify – how quickly did Miller gain this velocity in the off season? What did his training regime look like?

Interestingly, it has been noted that Miller suffered a flexor muscle strain, as well as the UCL tear. Given the urgency that Miller and the Diamondbacks had in accelerating Miller’s return to good-ness, there is a chance signs of discomfort were ignored along the way. When a flexor-pronator muscle is strained, the tension that the muscle originally supported during pitching is now transferred to the ligament. If you’d like to know more about this – there’s a very interesting discussion on flexor-pronator muscle tears/strains on the “fixing pitchers” podcast –

This is a very important note for young pitchers – do not ignore your body’s warning signs. If something doesn’t feel right, tell your coach and get it looked at by a doctor.

There are no red flags in this analysis for Shelby Miller – but had the strain been noticed a bit sooner, there is a chance he wouldn’t have torn his UCL.


Whiteside, D., Martini, D. N., Lepley, A. S., Zernicke, R. F., & Goulet, G. C. (2016). Predictors of Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers. The American journal of sports medicine, 0363546516643812.

MASH Report: Greinke, Lackey, and Tomlin

With the 2017 changes MLB Advanced Media implemented with their StatCast pitch tracking data, I’ve been scrambling to recode my pitcher injury finder. Well, it seems to be working fine and here are some pitchers it found to be concerned about.

Note: I have bumped up all 2016 and earlier values to be equal with higher 2017 readings.


John Lackey

It’s tough to tell if Lackey is hurt or he’s at a new, lower talent level. His last start was the most concerning. Here are his velocity and spin rates over the past two seasons.

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PITCHf/x Forensics: Zach Britton

Hot off the press, the world’s best relief pitcher has been sent to the Disabled List with a dreaded forearm strain. A strain, for those of you not familiar, is the tearing of a muscle or a tendon. This is a big deal in the forearm, particularly for a pitcher, because these muscles are the ones that protect the UCL during the pitching motion.

We are all familiar with the performance Zach Britton put out in the 2016 season – arguably, one of the most dominant relief pitching performances of all time. What was happening under the hood to lead to this injury?

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PITCHf/x Forensics: Rich Hill and Blisters

Pitch forks have emerged, and rage has exploded over the most recent Rich Hill trip to the disabled list – once again, for a blister. Hockey fans gearing up for the playoff run scoff, stating how their sport has players who take slap shots to the face and return in the same game – blisters? Those are a sign that baseball players are weak, pampered, and fragile. Why do blisters keep forming on Rich Hill’s fingers? What are the implications for changing his style that could prevent blisters from occurring all together? Why can’t Sidney Crosby grow a beard? Let’s get into the answers to these questions.

All of pitching revolves around applying the appropriate amount of pressure to specific areas at ball release, and causing the ball to spin about a certain axis. This pressure applied along the seams, generates friction, and spin on the ball. More friction? More spin. That’s why pitchers try the ol’ Icy Hot trick to get a better grip on the ball, and throw funkier pitches. Sorry if I got most of my pitching knowledge from Rookie of the Year – I flamed out as a player in High School.

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