I don't claim to be an expert, but here's what I do. It applies to all players, though, not just the mega-deep outfield, but it helps most with outfield and comparing players across positions.
First, to make a sort of 'common denominator,' I figure out what target totals to shoot for in each category. I look at the last couple of years of my league's totals and then totally guess at a number that should get me third or so in each category. I divide that # by the number of lineup slots for hitters, 11, to give me a score that the average player needs to attain to reach our goal. For example, if the goal is 1100 RBIs, if each player got 100, I'd reach my goal.
I make that value worth 5 points and set ranges on a 10-point scale. I come up with a minimum that significantly contributes to my team (maybe 50 RBIs in the example). Less than that gets 0 points. 50-60 gets 1 point, >150 gets 10 points. I then do projections for each player on each team's end-of-year roster, projecting what range I expect the player to fall in for each cat. Excel sums them up, and I have what I call a base score.I will then add fraction of a point adjustments to try and break ties. Last year, I did positional scarcity and multi-position eligibility, and 'hunch' points where I think there is a good chance the player will kill my projection in a good way.
It works for me, giving me an 'objective' way of differentiating that is still grounded in my opinions and what I am trying to do with my team. I will alter them constantly until the draft as I read stuff.
FTR, I have T Hunter and J Jones both at 14 (along with 17 other players, 6 OF), and I can't think of any tie-break points that will change that.
Biggio is a 16, but I like him so I might have been generous. Ibanez is a 12, and Floyd an 8 (I projected low ABs, I think.)
The method might not be mathematically sound, but it works for me. My initial rankings are on par with most of the ones posted in the Cafe, which was my acid test.
Done slowly over a couple weeks in December, it is not that much work and I can easily compare players now.
I also track my projections vs cat goals during the draft so I'd take a guy with higher steal points if I was lower on steals than I wanted to be, for example.