Originally Posted by
Kitai
Because SW no longer applies Vulnerable, MS drops from (effectively) 625%WD to 250%. Even know unusual situations where you are able to MS before the previous Vulnerable expires (either because you were focused starved during a burn or you just wanted to front load AE burn), the "baking in" of old Patient Sniper doesn't apply to MS, so the +150% modifier is nerfed to +100%.
Separately, Arcane Shot doesn't live in burst windows, even in 7.1.5. Rather, the build as it exists on PTR uses it (often!!) as a necessary evil.