Quoted from ifpapinball:

Yes. The original plan of 100/75/50/25/0 and adding that 4th year of decay was scrapped. This was due to the high pain in the ass level of carrying events under the 'old way' and 'new way' at the same time. Expanding that decay to 4 years meant we had to carry those 'old way' results for an extra year.
We'll revisit the decay once we have 4 years of 'new way' results.
Funny enough it actually had very little impact on the top 250-300 rankings by keeping that 4th year at 25%.

Quoted from desertT1:

I just did that last year, I don't wanna do it again.
I see what you are saying though. But, my state rank is more important to me than my world rank. At some point that will change, but for now I'm heavy in-state with hopes to travel a little this year.

Quoted from ifpapinball:

Here's the TGP cheat sheet:
http://www.ifpapinball.com/tgpguide

Quoted from ifpapinball:

It's the longest path for any one player. In strike (knockout) events the maximum number of possible rounds is what we list. Assuming each round is 1 game played per match you can't artificially create more rounds as players will be eliminated during the strike process.

Quoted from Snailman:

The 5 rounds for 2 players is the maximum # of meaningful games they'll play, or 20% TGP. The table isn't the # of rounds to get max TGP