Quote from blackdogUnderstand. But I imagine they still mix people with different skill levels, wouldn't make sense to have people only level 14 together... you never have the chance to improve(?).
It's not a simple level like 14, but it's the literal elo or glicko 2 score, so it's somewhere in the thousands (for example, a player may be ranked at 3562 or something). You're not going to get an exact match, but it's more logical and doesn't need modification over time as players get better.