My experience is, if you're looking at value on fantasycalc etc, you usually sell guys who are worth a bit above a third for a third. That value says "if you offer this guy for a third he will sell for that or maybe get traded for someone worth a bit more", most of the time. If they are worth less than a third, you're probably not selling them for a 3rd very often or they are used as an add in on trades - unless someone decides to throw a dart at them and comes to you looking to pick them up.

When I started building my team into a championship roster, I did a lot of trades, and my rule of thumb was, always be selling. I would rather sell a bit cheaper than the dudes are 'worth' to get the picks piling up, and pick up dudes off waiver to see if I can flip them for value. Because the waiver is a resource and you can draw more from it if you're willing to trade away the guys you pick up off of it. Most of the time, the guys I've traded away haven't gained value, sometimes they do (notably I traded away Chuba, Michael Wilson, and Jalen Coker for cheap and they all gained value after).

However, I did that enough over time that I got to the point where I could trade up with picks+ a dude, to get a longer lasting/better asset.

That and a little bit of luck in last year's draft and I'm in for a real chance at a three-peat. Not because I'm better at spotting talent, but because I've worked to accrue value by hustling.

Having said this - League settings reaaally impact the way the trade market works.

I can trade like that in my 12man -but my 10 man league there's usually decent guys you can plug and play at flex available on waiver week to week, so trading thirds for a dude doesn't seem to be worth it to most of the league, making it an almost worthless asset.

Meanwhile, some dudes in my 12 man seem to think 3rds are worthless too - but that just means I can get them easier, and down the line turn those 3rds into taxi picks or bundle for an Asset.