Hey guys I saw something weird on my last night Sha of Pride kill, I got lucky with way too much Gift of the Titans and only a single trap, and managed to score a rank on WoL (was 146 now 150 :c). Anyways, the thing is that my main source of dmg according to WoL was the mastery proc.
It happens quite often, it's a bit annoying but I'll take it. VERY rarely when the RNG gods deem me not worth does Sinister Strike beat out Main Gauche now.
The haste buff will increase your main gauche procs, but where main gauche appears on your damage done depends on how much mastery you have (for example, I'm at ~52% MG proc chance when raid buffed).