I already adjusted it, by calling him equal to Martin despite the numbers saying that Hayward was clearly inferior.
A 110 DRtg is terrible, no matter who your teammates are. Again, for context, Big Al put up a 104. Martin's numbers were the same or better than Hayward's pretty much across the board.
Hayward graded out as a pretty mediocre defender last year.
What I dislike about DRtg is that its a function of blocks, steals, defensive rebounds, estimated forced TOs, and estimated forced misses. Obviously, blocks, steals, and defensive rebounds hardly serve as an accurate for a player's true value, and estimating forced TOs and misses is just that - estimating.
It's especially pointless to compare the DRtg of a big man and a guard, because Hayward obviously does not rack up as many blocks, steals, or rebounds as Jefferson. Similarly, DRtg has Ibaka at a career 101 rating, while Westbrook's is just 106; I don't think anyone will argue that Westbrook is a worse defender.
Comparing just Martin and Hayward then, I think Fafnir puts it the best: the fact that Martin posted a 107 DRtg on OKC while Hayward was 110 on UTA is significant. I just wish there was a way to access Synergy stats for past years so that there's more quantifiable evidence though.