Height and scale?

[WEIRDWOLF]

For the MFCA Skills competition I am researching what distance a real 40 yard dash would be in relationship to the men in production.

In the photo I have lined up various men from Tudor, Miggle, Buzzball and FF.com. Each is in more or less a similar position. The lines on the card are 1/4 inch each.

It is easy to see that these are all different scales just like model railroads have N, HO, O and many other scales.

So my question is: assuming that these figures are based on an NFL pro player of aproximately 6 foot tall can we say that 1 1/4 inch equals 6 feet or what formula would be accurate?

What are your thoughts?
Do you also believe that these figures are based on 6 foot tall players?
Should they be classified as 2 or maybe 3 different scales?

If the manufacturers had a scale in mind, I would like to know what they based the sizes on. Maybe Reg and George could chime in on their thought process on this. I know that this has been discussed in the past but I would like to reopen it for those who were not around back then.