What are some trade rules that can/should be implemented? It's really hard to institute firm rules with something as objective as player values. It's kind of a "know it when you see it" type of thing.
"Know it when you see it" policies are the biggest problem, and disagreements about it happen every year. We had a long conversation in the baseball chat last year where I brought up a trade of mine that was rejected a few years back in response to another trade being allowed to go through.
I don't remember the exact trade, but it was a whole bunch of super star players who were currently on the DL who were keeper eligible that were traded for Mike Trout. After discussion, it was allowed to be upheld. But yet years back when I did the equivalent to the same thing to trade short term prospects like Altuve and Trea Turner to a team that was out of playoff contention for SP/Stanton for my own playoff runs, they were rejected and I was forced to make a less favorable deal for myself and the party involved who wanted the prospects.
The only justification that the people gave for voting against my previous trades while allowing that trade was "I've changed my mind/stances since then." Two separate trades in the same league who had the same purposes were given different consideration because of 1) their ideas about strategy changed and 2) who was involved at the and what it meant to their own winning chances. I don't think that is really great policy.
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I made a few suggestions last year about how I would change the trade system, and both at the time were met with "it's too late to change for this year."
Suggestion 1 (preferable) - Turn the powers of trade rejection over to commissioner review. As a league, we will come up with a list of violations that will cause a trade to be vetoed, such as trades that would ruin competitive balance to the league or trades that were crafted to abuse the keeper system. Really, we keep the trade rules we have always informally have but we formalize them.
This is the ideal system in my mind and still allows a "know it when you see it" approach. If there is a trade that is questioned by the community, it isn't left up to a 5 day voting/waiting period. Both the people for/against the trade can make their case to the league/commissioner and both sides can be heard fairly instead over time instead of people getting a notification and voting based on their gut reaction.
It allows the people making the trade to DM the commissioner and get his thoughts on the trade before the trade is made if it is questionable.
Though this hasn't happened to date, a possible problem that could happen with league votes is that bad trades are still allowed to be let through because there wasn't enough people active to review it. This wouldn't happen with commissioner review.
Suggestion 2 - We keep league voters, but we as league voters still need to come up with a list of offenses that should result in the voting down of trades. We increase the number of votes needed to veto a trade to 6 or 7 votes to make it as unanimous as possible while still giving room for inactive owners. We shorten the length of review to no longer than 3 days so that if a trade is rejected it can be resubmitted without having to wait a week.
Suggestion 3- Ban all trades. There are only about 2-3 trades a year anyways, and the ones that do happen always start arguments. This solves all problems, but goes against some of the fun of fantasy sports.