Early-season trades are always tricky. You don't want to give up on star players who you projected to have big seasons just because they have a bad game or two. Likewise, you don't want to pass up potentially great value players just because you didn't expect them to have breakout campaigns.
It's a delicate balance.
But that's where tools like the trade value chart can come in handy to help remind you of a star player's upside, or to evaluate the creeping value of those possible breakthrough stars.
As always, this is just a guide that doesn't take into account your specific team needs or league rules.