Absolutely, there are plenty of roles that are contest based, or the stats can show you how effective they are. The tricky ones are the defensive role players because without seeing ehat they are doing, or knowing what they are supposed to be doing, it is very hard to measure.
For example, when I watch Rioli live I can see that his role is to cover the extra defender, effectively to play on two opponents. We want to play a plus one back, which allows the opposition to do the same, but we don't want them to have easy outlet kicks from defence. Rioli covers his opponent and the spare, and often positions defensively instead of offensively to prevent them setting up an outlet, which effectively stops him getting the ball. Very hard to judge that role anyway but to watch how well he does it.