Someone has to be last, this year it was Sergey Sirotkin. At least in the case of Lance Stroll, he was able to show what he can do last year and will be able to next year too. Sirotkin doesn't have that luxury and might have to deal with this being his only F1 season.
He can at least take away one point from his year after Grosjean's DSQ in Monza gave him P10, there were also some decent qualifying performances, Monaco above any other springs to mind.
Unfortunately for Sirotkin, when a car is as bad as the Williams he had this year, all you can do is make sure you beat your teammate. Something he wasn't able to do. If nothing else, Sirotkin can hold his head high knowing he maintained his cool throughout the year and displayed impressive temperament.