Only in modern times!
Sierra Nevada's yeast is the same thing as Siebel BRY 96. BRY 96 is one of two yeast strains that were used at the old Ballentine Brewery in New Jersey long before Sierra Nevada came into existence.
In my humble opinion, the thing that separates West Coast-style IPA from modern East Coast-style IPA is the heavy use of Cascade and other citrusy hops. Modern East Cost-style IPA is more closely aligned with British tradition due to the fact that many of the early East Cost ale microbreweries and brewpub brewhouses were designed by Peter Austin and installed by Alan Pugsley. All Peter Austin-designed breweries use open fermenters and the Ringwood yeast strain, which is a two-strain Yorkshire-style yeast. Peter and Alan had a heavy hand in beer recipe design.