Upgrade availability on JFK - FRA

[yvrcnx]

I am booking JFK - FRA for 2 on an upgradeable Economy Class fare.
Since I am flexible on dates I have been checking on one way business class award seats from JFK - FRA.
If those show available in "Saver" is it a good indication that I will be able to upgrade using my miles from Y to C on those days also?

I am just wondering if there is any connection between the rewards seat and upgrade availability.

[9V-JKL]

Yes, they come out of the same bucket.

[yvrcnx]

Yes, they come out of the same bucket.

Thank you, that is what I was hoping for as it will make it easier to book a flight with the best chances of confirming the upgrade.