I can give you that for Harper. I don't think everyone is like Harper though. Sure, there may be a few bigger than life characters out there who care about such things, but most of the others will care about the whole picture and I'm sure all these agents have good finance guys who can draw a pretty good picture of what the different contracts/deferred money/tax implications are.
But anyway, you are contradicting yourself by saying they only care about AAV and total amount when you are saying the deferred money will turn them off. In Bryce Harper's case, he had some caveman type comment regarding how dumb the deferred money is, so it probably did make a difference to him. So yeah, Bryce Harper doesn't seem to get a lot of the nuances in financial matters or probably much else and wanted the biggest salary and wants all his money now. I tend to think he's the exception and not the rule.
It's by and large for most of them. They care about liking a clubhouse and organization far more than taxes. Most of them are making so much money that taxes are irrelevant.
Multiply your earnings by a factor of 10 and then tell me you would give two freaks about ~5% more taxes. You wouldn't. Particularly when compared to the culture of the company you would work with and how successful you would be able to be with that company.
Deferred money is far more lost revenue than a small percentage of taxes because it compounds over time and you can't invest it, while still getting taxed on it. That's why deferred amounts have to be so much more. Scherzer was projected to get 165-175 million, but the Nats blew all the offers out of the way. However, with the deferments, the total value of he contract to Scherzer when it's all over is far less.
This is why Harper/Boras said no to the deal the Lerners offered. It was so backloaded that it would have barely been half of the stated value by the end of the contract.
Deferring half your paycheck to 7 years from now is way more noticeable and impactful than a 4-8% tax increase.