I think you’re overthinking getting a $17 million raise. I’m sure he can get an $8 million deal even if he has a down season.
But yeah, it’s worth thinking through the issue. He can’t really get a bigger raise than the max, and if he does have a total outlier season (he suddenly becomes a legit modern 4 and/or gets really good at defense), his extension number next year doesn’t require cap-space to re-up.
I can see some downsides to your point but I mostly see this as a no-brainer for Collins. I think the biggest hitch is that I don’t know if it’s legal (I think you have to extend for several years in order to renegotiate… but maybe not)?