Here's something to keep in mind -- the actual stats of the mook don't matter so much as does how much lower they are than the PCs. Telling you that Vinnie the Snitch has an OCV of 5 doesn't help you if you don't know where the PCs should be.
A difference in OCV/DCV of 3 or more will mean that the character with the higher number will have a much easier time of hitting his opponent, while the character with the lower number will have a much harder time.
This page has a 3D6 distribution chart at the bottom. In the middle column they have percentage chance to roll under a given number. So let's say that Vinnie the Snitch has an OCV/DCV of 5. If Captain Amazing has an OCV/DCV of 9, then that means he needs a 15- to hit, whereas Vinnie will need a 7- to hit the good Captain. 15- means the Captain is hitting 95% of the time, while 7- means the gangster hits only 16% of the time (about 1 in 6). Of course if Captain Amazing decides to dodge, his DCV goes up by 3 and Vinnie needs a 4- (less than 2%) to hit. Whereas if our thug dodges, his DCV goes to 8 and the Captain still hits on a 12- (74% of the time).
So the OCV/DCV difference is important. Another thing to look at is the Speed differential. Having an extra 2 points of Speed is a big advantage in combat. A Speed 4 character will have a lot of trouble with a Speed 6 character if all other things are equal. The Speed 6 character can afford to block, dodge, take recoveries, or other defensive actions that the Speed 4 character can't.
Then look at the average damage of an attack compared to a character's Def + Con, and Def + Stun. If your heroes throw 12D6 attacks, the average damage is 42 Stun and 12 Body. Hitting a character with 8 Def means they take 4 Body and 34 Stun. If that exceeds their Con score, they are stunned and lose their next action. If it exceeds their current Stun total, it means they are unconscious. What this means is that superheroes can often "spread" their ranged attacks and affect multiple characters who are standing side by side. If Captain Amazing shoots his Optic Vision at a crowd of thugs, (4 guys sitting at a card table), he may be able to hit all four of them by only spreading a few dice. If his 12D6 attack lowers down to 8D6, then he's still doing 28 Stun on average, minus their 8 Def and each character is taking 20 Stun. He will almost certainly cost all those thugs their next phase, and might knock them all out.
In general, because I'm lazy, I tend to give generic thugs and mooks straight 15s in their primary physical stats. 15 Str, 15 Dex, 15 Con. Give them 10 PD and ED and a 3 Speed. 5 OCV/DCV and about 25 Stun is good. They'll carry weapons that are in the 6-8 damage class range. These are not meant to be threats to superheroes. They are very dangerous threats to normal people though. But most of the heroes in our games have OCV/DCV of 8 or above, Speeds of 5-7, and Defenses of 30 or so. They chuck 12+D6 attacks and so mooks are little more than targets for them. But that's how we like to play, mooks are just the warmup for the real fights.
