The dynasty community has an enormous amount of infrastructure around player valuation: rankings, ADP, trade calculators, positional scarcity models. And almost nothing around the person sitting across the table from you.
But here's the thing: player value is contested. Two informed managers can look at the same player and disagree by a full round. (Just look at De'Zhaun Stribling - I've seen him go at 1.11 and 2.12 in drafts this week.) Leaguemate behavior is actually more knowable. If someone has been acquiring RBs in the third round of every rookie draft for three years, that's not a coincidence. If they've been loading up on proven veterans all offseason, you know where to go shopping for draft picks.
The manager who knows what their trade partner actually values, not what the calculator says they should value, gets more deals done than the one who just knows KTC values.
What does your pre-trade prep actually look like on the leaguemate side?