Player skill is easily indicated by their win/loss ratio the easiest. However, you can't put players in the lowest bracket or highest bracket from the start. If we have tons of new, but very skilled game-players, always in the lowest bracket then we have bad players with bad experiences.
Either start players directly in the middle with a 1.0 w/l ratio or give them a test first to see how good they are.
From here, you simply match players with close w/l ratios. To simplify things for server-processing, you could round it off the nearest interval with intervals of 0.25 or 0.5 (calculated by dividing wins by losses, 6 wins divided by 2 losses = 3.0 w/l ratio. A 3.1 ratio would be rounded to 3.0, for example)
It really is that simple.
1. start players at 1.0 w/l ratio
2. put players with similar w/l ratios
3. round off by intervals to reduce strain on the servers tasked with matchmaking
CURRENTLY, BRINK has a system that ignores matchmaking competely. The purpose of matchmaking is to fight similar skill levels. Ranks in BRINK are not a w/l ratio, they are a total points number. Earn xp to gain levels, gain levels to gain rank every 5th level, and get matched with people of similar rank. This means that a player who's horrible at the game could eventually gain level 20/rank 5 and be matched with similarly-ranked players, or a player who's amazing at the game could start a new character and be matched with rank 1 players. This results in a completely random matchmaking system that doesn't make matches, it only picks whatever it can find.
Win/Loss ratio has been the most obvious and easy-to-understand method for matchmaking since win/loss ratios have existed (the beginning of time), so why would any developer ignore this? This is true matchmaking which I have yet to see in any game besides Halo 3 (anyone else have examples of matchmaking that actually works?)