I'm not in the mood to argue. Parses don't lie. Mercs are in the mid/mid-high of the DPS spectrum. Maybe you're not as good at Merc DPS as you think you are.
Note the length of the fights, many people upload failed attempts where their burst DPS was way higher than anything they can sustain, and therefore skew the results. It's unfortunate that the site doesn't show kill parses only. Also look at 8HM and 16HM only, most top players don't run SM.
And the reason why PT/VG is over performing and needs a nerf is because it does equal DPS to sniper and mara, which are pure DPS classes. BW has already expressed that pure DPS classes should be ~5% ahead of the rest. Now we all know that the gap between highest and lowest DPS class in game is definitely more than 5%, but it doesn't change the fact that PT/VG is over performing even if you only compare it to Sniper and Mara.
Again, this is all coming from PVE standpoint and DPS potential behind classes. PVP we've already discussed and agreed on what's holding Mercs back.