Matthew Monday, Analysis of Four Baseballs

Toward the end of August, I brought Matthew into work with me, and we had a task to analyze four different baseballs.  It seems like there are some claims in the baseball world that the current baseball is different from the ones in the past.  This year they are obliterating the record for the number of homeruns and pitchers are complaining that the baseball has changed.  Matthew and I wanted to closely analyze four different baseballs that we had that span the recent past.  Since we have some highly accurate instruments at work, we took it as a little project on a slow day in the summer.

So here’s what we did.  We had four baseballs.  They are listed under the column “Type.”  (1) Identified as the 2015 Major League ball autographed by Henry Urrutia.  (2) Second is new 2019 major league ball that was thrown to Matthew by Juan Soto at a game we went to in July.  Third is a ball I caught at batting practice at an Arizona Diamondbacks game some 15 years ago, roughly dated to 2004.  Fourth is a new 2019 ball from a minor league game this August, from Single A New York-Penn league. 

Here is a picture showing the four baseballs, with Matthew’s face as background. 

The balls are arranged from left to right in the way I list them in the paragraph above.  Visually, other than a slight discoloration for the 2004 ball, probably from age, the balls all look alike.

So we took the weight of the balls, the diameter of the balls (in two places), the width of the seams in several places, and the height of the seams in several places.  Let me preface that this is a very small sample size.  We could be led astray from a particularity of an individual ball.  But my hunch is that the conclusions we reach are pretty much true.

We took the weight of the balls on a very accurate scale which measured pounds to three decimal places.  See Table 1 below.  What is remarkable is that all three major league balls weighed exactly the same to the thousandth of a pound.  That is incredibly consistent.  Even the minor league ball was only 6 thousandths of a pound more.  Baseballs all weigh the same and just under a third of a pound or just over five ounces.  

Baseball Type	Weight (lbs)
2015 “Urrutia” Major League Ball	0.318
2019 “Juan Soto” Major League Ball	0.318
2004 Arizona Diamondbacks Major League Ball	0.318
2019 NY-Penn Single A Minor League Ball	0.324

Table 1

We also measured the diameter of the balls in millimeters using digital Vernier calipers, and here we did it in two places. Holding the close part of the seams up, we measured the diameter from the top to underneath, noted in Table 2 below.  Then we flipped the ball 90 degrees so that the wide part of the seams was up and measured that diameter, noted in column E.  Here is two interesting finds.  First off the two diameters for each ball were very close indicating the balls are very round.  Second, the two 2019 balls were all over 73 mm, the 2004 ball was almost two millimeters smaller.  The minor league ball was in between the two.  We conclude that the newer balls are slightly larger.

Baseball Type	Diam (Close)	Diam (Far)
2015 “Urrutia” Major League Ball	73.83	73.82
2019 “Juan Soto” Major League Ball	73.21	73.29
2004 Arizona Diamondbacks Major League Ball	71.77	71.59
2019 NY-Penn Single A Minor League Ball	72.39	72.31

Table 2, Units in MM

If you don’t know what Vernier Calipers are, you can read about them here.  

Here’s another conclusion, and this runs counter to conventional thinking.  Since the old balls are smaller but weigh the same, they are denser.  Matthew even said he could feel the old one being harder. 

Because Justin Verlander complained about the seams, we measured the seam width and the seam height.  Measuring the seam width was not difficult.  We stuck the tips of the calipers in the holes the threading makes.  We took four random measurements around the ball.  The average and standard deviation are listed in Table 3 below.

Baseball Type	Seam Width (Ave)	Seam Width (Std Dev)
2015 “Urrutia” Major League Ball	7.89	0.469
2019 “Juan Soto” Major League Ball	7.23	0.863
2004 Arizona Diamondbacks Major League Ball	6.95	0.349
2019 NY-Penn Single A Minor League Ball	8.50	0.179

Table 3, Units in MM

Measuring the height of the threads we used the depth gage part of the caliper, put it into a thread hole and measured the height to the top of the thread.  I’m not sure how precise this was, but we did see a stark difference, so the trend was probably true though the numbers might not be precise.  Again we took four readings around the ball for each ball.  Results are listed in Table 4 below.

Baseball Type	Seam Height (Ave)	Seam Height (Std Dev)
2015 “Urrutia” Major League Ball	0.86	0.361
2019 “Juan Soto” Major League Ball	0.84	0.113
2004 Arizona Diamondbacks Major League Ball	1.07	0.024
2019 NY-Penn Single A Minor League Ball	0.92	0.212

Table 4, Units in MM

Some conclusions on the seams.  There really wasn’t that much of a difference between the 2015 and 2019 balls.  But there was a difference between the 2004 and the newer balls.  Newer balls had wider seams than the old.  The minor league ball much wider.  The height of the new balls was some 20% smaller than the old.  Verlander is right.  The seams are lower on the new balls.  So the old ball had a narrower seam but taller than the new.  Also the standard deviations of the old ball were better, which means it was better manufactured.  The stitching process of the newer balls appears to be poorer, maybe to save money.

So here’s a list of all the conclusions:

1. New balls are slightly larger than previous but weigh the same.

2. Old ball is harder (denser) than the new.

3. The width of the seams on the new balls are wider.

4. The height of the seams on the old are higher.

5. The new balls are not as well put together as the old.

Does this all indicate the new ball travels farther?  One of the theories out there is that the lower seams on the new balls cause less drag when in flight.  I guess that’s true but how much I don’t know how to figure out.  Intuitively it doesn’t seem to me it would make that much of a difference.  But Verlander is right about the height difference. 

I would think the lower height on the newer balls might make it harder to spin off a breaking ball.  But then would the extra width of the seams on the newer balls help the pitcher spin it?  You would have to ask a pitcher which seam he would prefer.

Since the old ball were denser, you would think they were the more “juiced up” ball.  But I think the slightly larger new balls make it easier to see and hit. 

So do the new balls go further?  I don’t know, but this was a fascinating study.  Both Matthew and I learned a lot, and I got Matthew to see how some basic engineering analysis is performed.  He got to learn about weighing to three decimal places, measuring with Vernier Calipers, some basic statistics, tabulating in Excel spreadsheet, and drawing conclusions from data.  I hope you got something out of this too.