One of the arguments debates if Hogan equipment influenced Mizuno's design of their irons.
I believe it has.
First, let’s take a look at some Hogan irons.
Check out this link on how Sheets Design Group went about making the 1999 Hogan Apex Model.
One of the first things Sheets Design Group mentions is how Hogan preferred what he called an ‘underslung hosel.’ Hogan believed that the underslung hosel shifted the shaft’s axis closer to the sweetspot which made it easier to work the ball.
Next, Hogan liked what he called a ‘blade on blade’ design.
As Jeff Sheets says:
I honestly don’t know if this was Hogan’s name for the design but it became an element I clued in on when studying his work. This feature provided a thicker mass behind the face while keeping the center of gravity more heel-ward for easier workability. It also enabled a longer blade length without forcing the center of gravity further away from the shaft axis. – Jeff Sheets
Here’s a picture of my 1967 Hogan Percussion irons
As you can see…’underslung hosel’ with a ‘blade on blade’ design.
Let’s fast forward to 1983. Hogan came up with an alternate design of irons called the “Personal” irons set. As you will see, there’s no ‘underslung hosel’ and no ‘blade on blade’ design.
However, after that the Hogan company started to eliminate the ‘underslung hosel’, but still kept the blade on blade design. Here’s a look at the Hogan ‘BH Grind’ iron which was made in 1990. As you can see, no underslung hose, but the blade on blade design is there.
In 1987 though, Mizuno company started a line of irons called the Mizuno Pro TN-87. This was a limited set of irons that were designed by Tommy Nakijima in ’87, hence the name TN – 87.
As you can see, they practically look identical. Personally I believe Nakijima probably had a set of Hogan Personal irons and liked them so much that he decided to design the TN-87’s after them.
The success of the TN-87 eventually led to the MP-29’s which were an instant success and then the MP-14’s, which became extremely popular stateside. As you can see, the MP-29’s have a similar design to the TN-87 and the Hogan Personal.