Your suggestion seems quite efficient to me as it will make huge changes. Still, it requires a solid analysis of the data to make coherence with other existing criteria of the players.
I'll be short. The following figures about any player are already available and bring no interpretation :
- last trading date
- last trading price.
With an easy calculation, you can come out with how long the player was on a roster. You link that to a profit tax.
1 - 2 weeks : 100% profit tax (no profit made on the trade)
3 - 5 weeks : 75% profit tax (25% maximum profit made by seller)
6 - 9 weeks : 50% profit tax (50% max profit )
10 - 14 weeks : 25% profit tax (75% max profit made)
> 1 season : No profit tax.
Of course, current trade fees disappear.
Nothing else changes from current Trade scheme (bidding, setting sales price and how long the player is on TL).
You can imagine the player going to FA if no one bids. Could be complementary.
Seems quite simplier... And guess what, that's what Wolph was all about.
PS.: i divided 1 season time into 4 growing parts (2, 3, 4 and 5 weeks long) and accord them +25% of profit tax. Too simple to be fair enough, consider it as a sketch that can/must be sharpenned, but you got the main idea of it.