The problem with that approach is Chychrun needs a new contract. So do you get him a RD and then wait to see how he performs before locking him up? Or do you sign him and hope for the best? Keeping in mind that if you’re trading Chabot, you’re very likely either retaining or taking back bad money in the form of a forward. So if Chychrun gets a new deal and he still isn’t good, and you have money on the books from the Chabot trade, now we’re in a worse position than simply paying Chabot 8 million.
If you wait and he performs well, great - but there’s also risk in not being able to agree to a deal and you lose Chychrun too.
Chychrun’s value has a huge risk of getting worse if he signs a big contract he doesn’t live up to. I don’t see Chabot’s value getting worse really - he is what he is, but with less term and more likelihood for retention on our part, if anything he might be more valuable in two years than he is now. Doubly so if he plays well with a new partner.
I also just personally think the things Chabot does well, he does very well. So if both players have their warts defensively, give me the guy whose strengths are greater.