The only thing overspending gets you is agents trying to get you to overspend again.
I doubt there's "good will" value in overspending, Boras has a lot of clients, he's not going to violate his fiduciary duty by steering one to a lower cost deal because you overpaid for another.
And agents know who has the money and will to spend, Klentak has spent plenty of money the last two years, he just hasn't spent on a big money, long-term deal. $60M last year, and more this offseason.
First rule of negotiations is don't bid against yourself.
The best reputation Klentak can have is as a guy who'll pay market value but not overpay, so agents will come to him with real offers, but won't try to play him for a fool.