Well an average and a moving average should be different, as they are different calculations.
However, to see where the problem is we'd need to see the data itself. What's your source? Also, where are you getting the true averages about the nhl from?
If I go to this link Corsica | Team Query I can query each teams data game by game. If you turn the aggregate button off and run the date range 10/1/17 to today you can get all current data in a csv then I of course saved it as an excel file.
I have one but dont think I can upload it here.
Just as an example if I set the table calculation to show me a moving average of the last (5) and next (0) I have the following data points for time and goals scored
3/27/18 7.85 TOI 0 Goals
3/29/18 7.10 TOI 0 Goals
3/31/18 2.73 TOI 1 Goal
4/1/18 2.43 TOI 1 Goal
4/3/18 0.00 TOI 0 Goals
So I have a total of 20.11 minutes and 2 goals. So if I turn this into a rate stat per 60 minutes the calculation would be (60/20.11)*2=5.97, but the value I get on 4/5/18 is 19.4!
What if you change your measure to an average? It's currently set to sum, meaning it's getting your averages, and then summing them.
Also, your calculation in the workbook is (goals/time)*60, yet in your comment above you say the calculation is (60/time)*goals. I'm not sure what you're looking to do, but that may also be an issue.