The key point is that you cannot quantify good play beyond success, and you cannot use a program to really detect where the failure was.
Things are lost in the heat of battle. First boss of AK is easy, but I prefer DPS that let the rock adds get to me before they kill them, but some think it's cute to stun it {Over There} and kill it before it gets to me. Later in the fight when you're dealing with big red, rock adds take just a second longer to pick up if i couldn't drop the pile of rubble where I wanted.
(Now I'm fond of just tanking the rock adds too, and not killing them, but this is an example.)
Did the Paladin really fail at stunning Ifrit or has someone in the alliance got their stun in their rotation? You can check the log to see, but we all know how painful these logs are to navigate.
MVP has good intentions but it's an awful and exploitable system, especially this "no vote" notion.
Want more tanks to queue for randoms? Give them a reward for it, not necessarily tomes. Same for healers. DPS aren't as left out in the cold as they try to imply. Anyone can roll a tank and participate. If enough people do then dps becomes the prized role (lol, probably not).