Okay, so I've kicked it around and here's a preliminary concept of "gear score" I'd like to hash out.
Everyone knows about BattleBayItems and the associated spreadsheet, that shows item scaling per level, right?*
So let's make this super-simple and use those values for the gear score. I'm going to make an assumption here, feel free to correct me if you feel I'm completely off the mark:
Most items fitted to ships are at their level cap.
The reasoning here is that most people have trouble finding duplicate items more than parts or sugar - so that "Tier II" item is probably a Lv20, the "Tier IV" is probably a Lv40, and if you don't bring that Legendary "Tier 1" up to Lv10 you're wasting a lot of potential. But not everyone is. Notably, if this is an actual algorithm, Rovio will have the individual item levels and can more precisely calculate the gear score. I'm just being simple here for the sake of lazy math.
So breaking it down, we get:
Common: 4, 8, 12, 16, 20
Uncommon: 12, 20, 26, 33, 40
Rare: 18, 28, 37, 47, 57
Epic: 25, 38, 51, 64, 77
Legendary: 65, 74, 82, 91, 100
If we add up the scores for my team, we get:
77 57 57 57 51 57 64 57 = 477
65 64 64 65 64 47 38 = 407
37 37 37 37 33 37 37 = 255
47 47 47 47 38 47 28 = 301
47 47 25 47 47 28 47 = 288
A total of 1728 and an average of 346 "gear points" per ship.
For the enemy team, we get:
65 64 64 65 64 64 65 = 451
65 65 64 64 47 47 64 = 416
47 65 65 65 64 64 64 = 434
65 47 47 47 38 37 38 = 319
47 38 65 38 38 28 25 = 279
A total of 1899 and an average of 380 "gear points" per ship.
Whereas the infamy is literally a percentage apart (about 1.1% if you want to split hairs) the average "gear points" per ship is separated by a much more significant 34, or almost 10% (9.8%) - that's not even taking perks into account, or what said gear is. A Legendary Torpedo, Railgun or Sniper Cannon is a lot more match-changing than a vanilla Cannon and a Mortar.
*(You don't? Go there, it'll help you decide if it's better to switch to that Epic you can only push to Lv20, or stick with your Rare Lv40.)