by David Gassko
May 02, 2008
The first time I heard of
Ben Sheets
was in 2000, when he anchored the U.S. Olympic team in Sydney, pitching
a three-hitter in the Gold Medal match against Cuba, keying a 4-0
victory. From then on, Sheets, the 10th overall pick in the 1999 draft,
was permanently on my radar.
He was called up the next year, and though he struggled somewhat, ended
the season with an 11-10 record and a 4.76 ERA—not bad for a
22-year-old. He tired as the season wore on, and his ERA ballooned from
3.59 before the All-Star break to 7.06 after. Certainly, there was
still a lot of hope.
That hope, however, did not get fulfilled for three more seasons, until
Sheets properly broke out in 2004. That year, Sheets pitched 237
innings, struck out 264 batters while walking just 32, and posted a
sterling 2.70 ERA. It looked like he’d finally put it all together.
Unfortunately, that’s also when Sheets’ injury problems started. After
pitching well over 200 innings in 2002, 2003 and 2004, Sheets has not
approached that mark since. In 2005, he was sidelined with an inner ear
infection; in 2006, it was shoulder tendinitis; and in 2007, it was a
multitude of body parts.
When healthy, however, Sheets has been very good. Over 404 innings in
the past three seasons, Sheets has struck out 363 batters, walked 73,
allowed 45 home runs, and posted a 3.63 ERA. Last season, however, his
otherworldly walk ratio more than doubled (though it was still very
good), his strikeout rate fell, and Sheets’ fielding independent ERA (
FIP) ballooned to 4.10.
Amidst questions about his ability to stay healthy, there were suddenly
questions about just how good a pitcher Sheets is at this point. In his
first four starts this season, Sheets seemed to answer the latter
concerns definitely. In 28 innings, Sheets went 3-0 with 24 strikeouts,
four walks and just one home run allowed, all adding up to a 0.96 ERA.
Unfortunately, the former questions have reared their ugly head. Sheets
complained of tightness in his triceps after his fourth start, and so
the Brewers skipped his next turn in the rotation. He came back
Tuesday, but walked seven hitters while striking out just two in five
painful innings. Sheets attributed the poor outing to rustiness, but
that certainly is not an encouraging sign.
So today, we’ll take a careful look at the pitcher that is Ben Sheets.
We’ll look at what PITCHf/x data can tell us about him, but we won’t
stop there. I’ve enlisted the help of Dan Loeterman, a student of
mechanics, who will give us a detailed breakdown of Sheets’ mechanics,
and the help of our own injury expert
Chris Neault to analyze Sheets’ long history injury and tell us what it might mean for his future.
There’s a lot of PITCHf/x analysis being done online these days, as
well as a lot of mechanics stuff, and some injury analysis too, but I
think the three are much more powerful descriptive tools when combined
than when they are separate, so I’ll try to write this kind of an
article occasionally from now on. Let me know what you think about the
format; my e-mail is available at the bottom of the article.
What does he throw?
(Note: We’re going to focus on data from Sheets’ first four starts in 2008, since he did feel out of sorts on Tuesday.)
The amazing thing about Sheets is that his dominance rests on basically
just two pitches, his fastball and his curve. Sheets throws his
fastball 61 percent of the time and his curveball makes up 35 percent
of his pitches; the other four percent are changeups. Sheets’ pitches
are really easy to identify if we plot vertical movement versus pitch
speed:
You can see that Sheets’ pitches form three distinct clusters: a
fastball that averages about 92 mph and 11.3 inches of vertical
movement (compared to a theoretical spin-less pitch thrown at the same
speed—obviously, Sheets’ fastball does not literally move up); a
changeup that averages about 85 mph and 6.6 inches of vertical
movement; and a curveball that is thrown at 79 mph and has 4.8 inches
of drop to it.
Already, we start to see some of the reasons for Sheets’ dominance. His
fastball is very much fast, especially considering that pitch speeds
are considerably slower in the cold month of April (especially in
Milwaukee), and it has about two-and-a-half more inches of rise to it
than your average fastball. There are going to be lot of
swings-and-misses on that one.
Sheets’ curveball is still nastier—t comes in a few miles per hour
faster than your average curve, but somehow it drops an inch and a half
more. Ten percent of Sheets’ curveballs result in swinging strikes,
while 27 percent of the time batters are too confounded to even swing
at a curve in the strike zone, versus a league average of 19 percent.
Let’s also look at the customary plot of vertical versus horizontal movement:
As is normal, Sheets’ fastballs move in on right-handed batters (and
away from lefties), while his curveballs move away from right-handed
hitters. What’s interesting, however, is that Sheets’ fastball has a
lot less horizontal movement than an average fastball, more than
two-and-a-half inches less. For those worried about data quality
issues, Josh Kalk’s
corrected data from 2007 shows much the same thing.
Of course, Sheets makes up for that lack of boring action with extra
vertical movement and pure speed. In fact, I wonder if that is a
conscious tradeoff.
Anyway, as good as it is, Sheets’ pure brilliance does not come from
the quality of his stuff, but its accuracy. Sheets throws all his
pitches for strikes: Just 34 percent of his fastballs are called balls,
only 31 percent of his curveballs (versus a league average of 40
percent!), and only 27 percent of his changeups (though the sample size
here is tiny). In total, two-thirds of Sheets’ pitches are strikes,
compared to an average of around 62 percent.
To summarize the total picture here, we can see that Sheets is still a
very good pitcher. His fastball and curveball are both very good
pitches, and his accuracy means that hitters can’t lay off those
pitches and hope Sheets is wild when they face him. In the next two
sections, we’ll try to answer two questions:
(1) Mechanically, what does Sheets do well and what does he do poorly, and
(2) Does his propensity for injury mean that we’ll never see Sheets’ great pitching for any prolonged period of time?
Sheets’ Mechanics
by Dan Loeterman
Ben Sheets does an excellent job of keeping his pitching motion tight
and compact, and when healthy he’s been one of the majors’ best
pitchers. He has good rhythm, breaking his hands as he lowers his leg
from the kick, and his weight isn’t too far forward on his step.
Despite the high leg kick, Sheets’ lower body is not especially active
(discussed below), though he compensates by bringing the ball in a wide
circle—the wider the circle going into release point, the more
power—and slingshotting it toward home plate. He pushes off well with
his back leg and has a strong follow-through with that back leg,
indicating a good transfer of power from the lower body to the arm.
But Sheets doesn’t use the rest of his body to generate nearly as much
power as he could, and he doesn’t lead toward home plate well with his
front shoulder. To demonstrate this, I’ve compared Sheets’ delivery to
Josh Beckett’s at a few crucial points.
The Kick
(Note: In all these pictures, Sheets is on the left, Beckett on the right.)
After a pitcher kicks his leg, he is supposed to bring the foot right
back to the ground and glide along the ground, keeping the weight even
between the front and back feet until the last moment, when he opens
his hips and generates power using his lower body and core.
This comparison shows each pitcher as his leg is on the way down from
the kick. Sheets' leg is completely straight and pointed toward third
base as he lowers his leg from the kick. Instead of leading with his
knee and preparing to open up his hips in a rush of torque and power,
he’s preparing to lazily swing his foot around instead. This delivery
gives him about as much power as if he was pitching from the slide
step, and he has to generate all the power from his back leg.
Beckett, on the other hand, has kept his knee bent and is preparing to swing the knee open.
This image shows how exaggerated that kick toward third base is:
The Step
This image is taken from the moment each player’s front foot hits the
mound. Beckett is leading with his shoulder toward home plate, and is
keeping his shoulder closed in until the last second, as a good hitter
would. Even as he rotates his hips, his momentum is forward. His body
is completely perpendicular to the ground, and he’s preparing to open
up that front shoulder and use his core and upper body strength to
fling the ball forward.
Sheets, by contrast, is leaning way off toward first base; his momentum
isn’t forward, but to the side. His shoulder has already opened up and
is pointing to the left of home plate. At this point, he’ll rely more
on arm strength to deliver the pitch.
Arm Slot
With these pictures, we can compare the pitchers’ arm slot. A lot has
been made of Sheets’ arm slot, and he admitted during spring training
this year that command of his arm slot comes and goes.
The trick with arm slot is to get the right combination of torque, from
side to side, and moment forward. Come too far over the top and your
body won’t be able to give you enough torque and power; bring your arm
too low and the power will be in the wrong direction entirely, and
you’ll put too much stress on your arm.
A “three-quarters” arm angle, where the pitcher roughly makes an L with
his arm as the point of release, is generally believed to be the best
compromise. To understand why that arm angle provides more power, plant
your feet on a solid surface and hold your arms straight out from your
body to each side, so they’re parallel to the floor. Ball your right
arm into a fist. Now rotate your upper body to the left, and then all
the way back to the right. Notice how much torque is built up in your
right fist. Now hold your arms straight up like a referee signaling a
touchdown, ball your right fist, and repeat the exercise. Notice how
little torque you’ve build up. By having a lower arm angle, you can
transmit the side to side energy of your shoulders and hips into
velocity.
But instead of forming an L, Sheets’ arm slot is too high. And while
Beckett’s shoulders are square toward home plate—he’s waiting long
enough to open up his body until the exact right moment—Sheets'
shoulders are square to the left of home plate, just as his front
shoulder was pointing in that direction. Falling off to the side may be
one reason why Sheets has such a tough time finding the right arm slot;
because he is leaning so far to the left side, it’s almost impossible
for him to get the ideal three-quarters slot by lowering his right arm.
His arm is dragged up by his body, as if to compensate.
(One advantage of a more over-the-top arm slot like Sheets’ is the devastating 12-6 action he gets on his curveball.)
Follow through
Finally, we have each pitcher’s follow through. Once again, you can see
that Sheets is leaning way off toward first base, while Beckett follows
through toward home plate.
Obviously, Sheets has proven to be a very good pitcher when healthy, but these aspects of his mechanics often work against him.
Why can’t he stay healthy?
by Chris Neault
Believe it or not, Sheets was not always labeled “injury-prone.” In
fact, from 2001 to 2004, he stayed quite healthy, and accumulated a
heavy workload, logging 151.1, 216.2, 220.2, and 237.0 innings pitched
in each of those years, respectively.
He was able to start 34 games for the Brewers in 2002, 2003, and 2004.
After an absolutely fantastic 2004 season that saw Sheets tally 264
strikeouts versus only 32 walks, while allowing only 201 hits in 237
innings, it looked as though Sheets was on his way to being a household
name amongst the greats of the game.
Then the injuries began to pile up for the three-time All-Star:
- In 2005, he sustained what was termed a "viral infection" of
the inner ear, and missed 30 games due to dizziness and altered balance.
- A torn latissimus dorsi muscle in his right shoulder occurred in late August and ended his season.
- In the offseason, he had a microdiscectomy back surgery to correct
a herniated disc in his lumbar spine (low back). While this is
considered to be a minor back surgery, it should be noted that no back
surgery is "minor." Having any spine procedure as a 27-year-old is
somewhat concerning, and leads me to wonder how his overall core
conditioning is.
- The 2006 season saw Sheets begin the year on the DL due to a posterior shoulder strain.
- Tendinitis of the right shoulder landed him back on the DL in early
May. He spent a great deal of time on the DL with this injury—a span of
72 games passed before he returned to action.
- A torn tendon in his right middle finger sidetracked his 2007
campaign; he was sent to the DL in July and missed a course of 40 games.
- After returning for a few starts, a minor hamstring strain was
enough for him to miss the final eight games of the regular season.
- He has also dealt with an array of minor injuries that did not
require much, if any, missed time (right pectoral strain, left groin
strain).
The latest injury for Sheets has been coined, “right triceps
tightness,” but it might as well include the rotator cuff. In my
clinical experience, I have seen very few baseball pitchers present
with a pure, isolated “triceps strain”—rather, there is almost always
an involvement of the rotator cuff muscles in what is called the
“Quadrangular Space.”
Why do these injuries continue to mount for Sheets? The culprit appears
to be his high arm slot. Although it’s partly responsible for the large
12-6 curveball, it’s also responsible for taxing the rotator cuff to
the max. As a rule of thumb, the higher the arm slot, the harder the
rotator cuff and biceps must work to stabilize the head of the humerus.
This places stress on the rotator cuff interval, which includes
ligaments in the front of the shoulder that also add stability. Let’s
talk about this in a little more detail.
Sheets places a lot of horizontal abduction on his shoulder when he
brings the ball behind him at the beginning of his throwing
sequence—prior to the cocking phase. He brings his pitching arm far
behind his trunk, and basically points his elbow and forearm beyond
second base (to the right side of the infield). This is the beginning
of the “wide circle” that Dan was talking about. This motion places
stress on the anterior shoulder structures such as the anterior joint
capsule, coracohumeral ligament, pectoralis major, biceps, and labrum.
When the arm reaches this position, the shoulder is internally rotated,
and is decelerated passively by the anterior shoulder structures and
eccentrically by the posterior rotator cuff musculature. The small
muscles of the posterior rotator cuff then need to contract to begin
the external rotation phase, in an attempt to bring the shoulder into
the cocking phase.
Keep in mind, these muscles are quite small, and are not “power”
muscles. The rotator cuff is a group of deep stabilizers, responsible
for fine-tuning motion and controlling the head of the humerus in the
socket.
The shoulder is still behind his body in horizontal abduction at this
point. He does not use his lower body effectively, as Dan pointed out,
and incorporates a heavy trunk lean towards first base, which in turn
helps bring his pitching arm up into his high arm slot.
Just before this happens, as the shoulder is reaching the maximum
amount of external rotation, the internal rotators of the shoulder
powerfully contract to decelerate the shoulder. This would include the
subscapularis, pectoralis major, teres major, and latissimus dorsi.
These muscles then contract forcefully to help bring the pitching arm
forward toward home plate.
Following release, the posterior rotator cuff muscles decelerate the
pitching arm once again, in addition to the latissimus dorsi.
That is a lot of work for the shoulder to endure—especially in the case
of Sheets, who displays a tremendous range of motion at his shoulder
during his whole pitching motion. Plain and simple, he has a lot of
motion to control with his rotator cuff, which leads to his frequent
injuries.