QB Brock Purdy Thread

Originally posted by Dshearn:
"The interesting thing with sin is that it's a periodic function. That means there are times when a LOWER trajectory would take more initial velocity than a higher one, and there are times when a HIGHER trajectory would take more initial velocity. You brought up the fact that a zero trajectory would take infinite velocity. That's true. So would a 90 degree trajectory."

He agrees with you.... until Newton's 3rd law comes into effect....and at that point you would need more velocity to reach higher to fall farther away.

He has already dragged me into the deep end and left me there to drown....so maybe I am wrong....but I would guess that is what he meant.

I think with a football, what is missing from all this math talk is Rotation and how RPM of the ball effects the stability of the throw so flutter does not waste energy.....

RPM takes hand and arm strength.... things we commonly refer to arm strength.

It's better to just assume all the hand strengths to be "equal" or "even" to each other...to get enough of a spiral by this stage of their careers.

Then compare the real difference, which is arm strength.

But if you again want to go the way of the nerds... I remember this exerpt from an article:

"An article in the American Journal of Physics (2003) that measured the coefficient of drag of a spinning football to be around 0.05 to 0.06."

And so assuming these following things...

The air resistance is proportional to the square of the velocity of the football
The Mass of the ball is 0.42 kg.
The density of air is 1.2 kg/m3.
The coefficient of drag for the football is 0.05 to 0.14 (initial)
Typical initial speed of a thrown football is around 20 m/s

w/ all of these forces acting on the ball:

The furthest throw goes from 45 degrees to

The more you ignore drag/spin/air resistance, the closer it gets back to 45° as the furthest throw.

is this the brock thread or physics class?

Originally posted by Young2Owens:
is this the brock thread or physics class?

QB playing so well the WZ doesn't know how to handle it, this is my theory

Originally posted by Young2Owens:
is this the brock thread or physics class?

What's wrong with people posting informative information? I'll take that over the arguing, trolling and all around stupidity any day.

Originally posted by Memphis9er:

Originally posted by 5_Golden_Rings:

Originally posted by 49erKing:

Originally posted by 5_Golden_Rings:

Originally posted by Giedi:

Originally posted by brodiebluebanaszak:

Originally posted by Giedi:

Originally posted by tankle104:

#49ers QB Brock Purdy has (so far) simultaneously improved in time before throw, air yards per attempt and yards per attempt.

2022: 2.93 seconds, 7.0 air yds/att., 8.4 yds/att.

2023: 2.56 seconds, 7.2 air yds/att., 9.1 yds/att.

Ball out quicker but still gaining more yards.

— Nick Wagoner (@nwagoner) October 2, 2023

Arm is definitely stronger than Montana's.

No not really. They both throw extremely catchable balls on all their different types of throws though. Both elite there.

Disagree, I remember Montana's long balls had more arch to them. Early in Montana's career (Before Rice) he had long ball issues. Which are not a big deal during the early years as he had Wendell Tyler. That Aiyuk 40+ yard throw was a flatter trajectory than Montana's usual deep throws, as I recall it.

Having a lower trajectory on deep balls all the time means your arm isn't as strong, because you have to cut out the wasted motion. You think Russell Wilson has a weak arm? His deep balls are more tear drop than anyone's I've ever seen.

The second the ball leaves your hand, the only forces working on it are gravity and friction. A high arching ball travels a further net distance than a flattened one. It takes more arm to throw more distance. QBs who depend on a flat arc for deep balls probably do not have as strong an arm as those who don't.

HOWEVER, it could also merely be a preference. The QB maybe doesn't anticipate as much as the tear drop guy and has to sling it to get it there in time, or perhaps they're paranoid about the ball taking a long time to get there.

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EDIT: before I get tarred and feathered, I'm not talking about Brock. His arm is plenty strong enough to hit every throw you need to wear a gold jacket. I'm just talking theoretically. If you HAVE to have a low trajectory to throw deep, your arm isn't as strong as someone who can easily do either.

Any science behind this? I think if someone wants to throw deep, if they have the time, and it makes sense, they "naturally" conform to throwing with a higher arc/higher trajectory. I mean that's how I feel when I play catch with the guys. If you're trying to laser it while going deep I think that actually means you have a stronger arm than most.

Yeah. Pythagoras (Extended to curves; the same principle applies, you just add up the infinitesimal distances via a line integral, but it's essentially the same thing. In Euclidean geometry, a straight line is the shortest path between two points.). A high arcing ball travels more distance. As the ball is not getting any additional force as it leaves (basic physics), what you put into it upon release is all it has. So throwing with a high arc doesn't give you some boost. That's not how physics work. Draw a free body diagram. Only gravity and friction are of any consequence once it's released.

So, the high arcing ball is thrown further in actual distance traveled than the low arcing one.

Which means, if you MUST throw with a low arc to get it there, your arm is weaker. (By arm strength I mean how far you can throw the ball, but I see no reason why velocity and distance would be different as a measure of arm strength unless the QB has mechanical problems which make one of either his distance or velocity throws more inefficient.)

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EDIT: Just to be clear, however, I do believe that the most likely reason most of the time for why some QBs throw with a low arc and some don't is that the low arc guys either have poorer deep anticipation or don't trust their accuracy and timing as much, or fear that a super fast safety might catch up and make a play. In other words, I think a lot of low-arc deep ball guys COULD throw tear drops but choose not to.

Kaepernick used to throw frozen ropes, I don't think he could put air under it. It takes more strength to throw those low angle passes because you have to put more mustard on it to get the ball to go where you want it. The downside is those balls are much harder to catch. Putting air under it means you don't have to throw it as hard to get it to the target, and the balls are much easier to catch. Josh Allen is probably the best pure arm talent that can do either as needed.

A lot more goes into the equation than arc. I don't even know if arc is the correct description because your talking about initial launch angle, force that propels the ball, spin on the ball that allows its shape to cut through the air, and gravity. There's a proper equation for projectile motion.

In summary, Brock's arm is fine.

Originally posted by random49er:
It's better to just assume all the hand strengths to be "equal" or "even" to each other...to get enough of a spiral by this stage of their careers.

Then compare the real difference, which is arm strength.

But if you again want to go the way of the nerds... I remember this exerpt from an article:

"An article in the American Journal of Physics (2003) that measured the coefficient of drag of a spinning football to be around 0.05 to 0.06."

And so assuming these following things...

The air resistance is proportional to the square of the velocity of the football
The Mass of the ball is 0.42 kg.
The density of air is 1.2 kg/m3.
The coefficient of drag for the football is 0.05 to 0.14 (initial)
Typical initial speed of a thrown football is around 20 m/s

w/ all of these forces acting on the ball:

The furthest throw goes from 45 degrees to

The more you ignore drag/spin/air resistance, the closer it gets back to 45° as the furthest throw.

What if you got the wind at your back? I imagine a higher trajectory would fare better

Originally posted by SLCNiner:

Originally posted by Young2Owens:
is this the brock thread or physics class?

What's wrong with people posting informative information? I'll take that over the arguing, trolling and all around stupidity any day.

no! i want troll posts!

Originally posted by Young2Owens:
no! i want troll posts!

Brock playing too well to even have anyone even troll. Just left with people trying to manufacture outrage.

Originally posted by 49erFaithful6:

Originally posted by Young2Owens:
is this the brock thread or physics class?

QB playing so well the WZ doesn't know how to handle it, this is my theory

I'm all for it!

Originally posted by random49er:

Originally posted by Dshearn:
"The interesting thing with sin is that it's a periodic function. That means there are times when a LOWER trajectory would take more initial velocity than a higher one, and there are times when a HIGHER trajectory would take more initial velocity. You brought up the fact that a zero trajectory would take infinite velocity. That's true. So would a 90 degree trajectory."

He agrees with you.... until Newton's 3rd law comes into effect....and at that point you would need more velocity to reach higher to fall farther away.

He has already dragged me into the deep end and left me there to drown....so maybe I am wrong....but I would guess that is what he meant.

I think with a football, what is missing from all this math talk is Rotation and how RPM of the ball effects the stability of the throw so flutter does not waste energy.....

RPM takes hand and arm strength.... things we commonly refer to arm strength.

It's better to just assume all the hand strengths to be "equal" or "even" to each other...to get enough of a spiral by this stage of their careers.

Then compare the real difference, which is arm strength.

But if you again want to go the way of the nerds... I remember this exerpt from an article:

"An article in the American Journal of Physics (2003) that measured the coefficient of drag of a spinning football to be around 0.05 to 0.06."

And so assuming these following things...

The air resistance is proportional to the square of the velocity of the football
The Mass of the ball is 0.42 kg.
The density of air is 1.2 kg/m3.
The coefficient of drag for the football is 0.05 to 0.14 (initial)
Typical initial speed of a thrown football is around 20 m/s

w/ all of these forces acting on the ball:

The furthest throw goes from 45 degrees to

The more you ignore drag/spin/air resistance, the closer it gets back to 45° as the furthest throw.

AActually this started as an observation that Montana might have had a stronger arm than purdy because he threw the ball with more Arc downfield.

That's how it started. I'm still not convinced that throwing the ball with a particular Arc shows you have more or less strength than another individual who throws the ball with a different Arc. I see the two is independent. But it's interesting to read what so many people have to say about Newtonian mechanics and the throwing of footballs.

Originally posted by random49er:

Originally posted by Dshearn:
"The interesting thing with sin is that it's a periodic function. That means there are times when a LOWER trajectory would take more initial velocity than a higher one, and there are times when a HIGHER trajectory would take more initial velocity. You brought up the fact that a zero trajectory would take infinite velocity. That's true. So would a 90 degree trajectory."

He agrees with you.... until Newton's 3rd law comes into effect....and at that point you would need more velocity to reach higher to fall farther away.

He has already dragged me into the deep end and left me there to drown....so maybe I am wrong....but I would guess that is what he meant.

I think with a football, what is missing from all this math talk is Rotation and how RPM of the ball effects the stability of the throw so flutter does not waste energy.....

RPM takes hand and arm strength.... things we commonly refer to arm strength.

It's better to just assume all the hand strengths to be "equal" or "even" to each other...to get enough of a spiral by this stage of their careers.

Then compare the real difference, which is arm strength.

But if you again want to go the way of the nerds... I remember this exerpt from an article:

"An article in the American Journal of Physics (2003) that measured the coefficient of drag of a spinning football to be around 0.05 to 0.06."

And so assuming these following things...

The air resistance is proportional to the square of the velocity of the football
The Mass of the ball is 0.42 kg.
The density of air is 1.2 kg/m3.
The coefficient of drag for the football is 0.05 to 0.14 (initial)
Typical initial speed of a thrown football is around 20 m/s

w/ all of these forces acting on the ball:

The furthest throw goes from 45 degrees to

The more you ignore drag/spin/air resistance, the closer it gets back to 45° as the furthest throw.

20m a second is what 44? 45 MPH......weakkkkkk noodle......

the things you learn on the zone.....

The ideal Rotational RPM is 600 a second.... According to Zebra research, the average NFL QB is around 700 rpm and the highest I could find was 890 by a high school guy....so clearly most QBs are going to break the 600 threshold....

"forward speeds between 10 and 30 m/s the drag coefficient is in the range of 0.05–0.06. It is smaller by about 10% if the
ball is spinning at 600 rpm"

30m a second is around 67 mph... Since low velocity does not seem does not seem to effect drag and few QBs are chucking past 67mph the only question left is what does extra rotation do if anything.

Then of course the angle change at 55 or 60....

Originally posted by Shorteous:

Originally posted by 49erFaithful6:

Originally posted by Young2Owens:
is this the brock thread or physics class?

QB playing so well the WZ doesn't know how to handle it, this is my theory

I'm all for it!

This giants game sucks....we will all know more then we should know about football trajectory....then someday some random poster is gonna say something and we will necro post bomb him...... let that guy deal with all the maths...... ( not our Random....but some random random guy....)

Damn, if I had known all that geometry, trig, and algebraII stuff would help me in the Zone, I would have paid attention

just think of how much more d jones gets paid than brock

Originally posted by SLCNiner:

Originally posted by elguapo:

Originally posted by SLCNiner:
Just gonna leave this here. I know we've only played 1/4 of the season, but he is getting better and may very well go up. Sorry, don't think Total QBR measures arm strength.


Total QBR All Time

Brady 2007 - 87.0
Manning 2006 - 86.4
Purdy 2023 - 84.5
Rodgers 2011 - 83.8
L Jackson 2019 - 83.0
Brees 2011 - 82.3
Brees 2009 - 82.0
D Garrard 2007 - 80.9
Manning 2009 - 80.7
Mahomes 2018 - 80.3

Boom. So much for regressing to the mean like some people were incessantly claiming when his believers were saying all along that there is WAY more room to get better than teams figuring him out

Yeah man, there's nothing to figure out, other than exactly HOW you might want to lose. He is the missing piece to Kyle's offense. Already the best QB has ever worked with.

Right on right onnnnnn