As a simple, effective solution to the skill-gap, which would function regardless of the skill-matching system, a handicapping system can be employed.

It would work by basically giving the losing player extra equipment. The further behind the player(s) get, the better equipment they spawn with. When they are only 3 points behind, they might spawn with 100/50 and a RL (in addition to the mg and gauntlet). If they get to 10 points behind (in duel, let's say), they spawn with 200/200, all weapons and ammo, and a quad damage.

Obviously, in a gamemode like CA, the handicapping system would work the opposite: meaning, the winning players would spawn with less. You can't really give the losing players more stuff off the spawn (aside from quad, haste and regeneration). If the losing players spawned normally, and the winning players spawned with 100/50, gauntlet, mg and RL only (and possibly even strafejumping disabled), it would certainly close the gap.

With these sorts of rules, the scores would be closer, and the ruleset could be disabled or enabled through a simple vote or when creating a server. It would give newer players the reason they need to continue playing. And in some ways, it would make the game more difficult for experienced players. Obviously, it's easier to play against 100/0, gauntlet/mg off the spawn than 200/200, everything + quad (and strafejumping disabled for yourself).