I'm trading to trade for a guy who won't accept a trade to my team. Although I have a better record (past the 28 game mark), and I had a better record the year before. I thought this was all record based. Any insight? 

Yep just one game. How much of a bigger lead until he'll accept? 

Not sure.    But I've seen them reject with 1 game leads.   I would guess 3 since that's how long it takes a trade to process.

It may go by waiver wire priority, which is determined by team record.  But I'm not sure if waiver wire priority is recalculated after each game, or once a day when waiver claims are processed at the 3am cycle.  I've never bothered to check.

If it's the latter, then there could be a lag in which you have a better record in the evening, but started the day either tied or a game behind in the morning.  Which would explain the rejection.