OTC doesn't always recalculate for me when I switch back and forth, but I'll give it a shot:
Using the OTC numbers, before any restructure, the Rams can cut Quinn before the 2019 season without any dead money under the cap. (Approx. 955k hit for a cut before the 2018 season).
An OTC maximum restructure in 2018 reduces Quinn's 2018 cap number from about 12.4 M to about 7.1M but increases the 2019 cap hit from about 12.9M to about 18.2M. This hypothetical restructure also means that cutting Quinn before the 2019 season will cost the Rams about 5.3M in dead cap space. That's 5.3M more than before the restructure.
I severely doubt Quinn can legally up his performance in 2018 to be worth 18.2M in 2019. Cheers to those who disagree.
So a 2018 restructure (1) gets the Rams more cap space in 2018 at the cost of (2) a ridiculous cap hit for 2019; and (3) dings the Rams for a sizable dead cap if/when they cut Quinn before the 2019 season (because there's no way he'll be worth a 18.2M cap hit).
Of course, YMMV.