A lot of times people will talk about free agents and waiver wire pickups and say, "He's not gonna hurt you." What are they talking about and how did they arrive at that conclusion? And, why don't the rankings support the theory?
Empty qualitatives, that's why. Allow me to explain.
Guys that are supposed to "not hurt you" are the players with decent qualitative statistics, which are perceived as harder to support and maintain over time. Those qualitative stats are things like batting average, ERA, and WHIP. Ratios and averages and not counting stats.
By the way, "counting stats" is a term that bothers me... I'm not sure why. All I can come up with is that it feels like someone is trying to dumb down the game for the masses. Let's just say "quantitative statistics"... cool?
So anyway, quantitatives are easy to track and easy to see increasing... When you go from 20 stolen bases to 23 in a couple of days it's easy to see exactly what happened. When your team ERA goes from 3.98 to 3.95 most people just aren't really interested. I guess it just takes more brainpower or something.
Nevertheless, you're only tracking 10 stats in most leagues and they are all equal. Here's the crux of what I am saying: If you pick up a guy who hits .300 with next to nothing in the quantitative stats, I've got news for you - he's hurting you. There is a cost to starting a guy (or even rostering a guy) who only delivers in one category, regardless of what that one category is.
I'd rather pick up a free agent who hits .255 with decent HR's, RBI, and R's (I don't know, Juan Rivera?) than a Jeff Keppinger type of guy who will hit for a pretty good average and not too much else. Keppinger is the kind of player that elicits comments like, "Pick him up, he's not gonna hurt ya." I beg to differ.
And listen, last thing here, Keppinger will produce some numbers in the quantitatives. What we are concerned about is the delta between what the average player gives you versus what the free agent pickup in question will give you.
Keppinger's quantitatives will be too far below the average for his .290-ish batting average to matter much to you. You're probably going to be able to find someone who will deliver better statistics versus the average across the board. And that, incidentally, is where those in-season rankings come from and why a "not gonna hurt you" kind of player is generally ranked worse than some other options that I guess are supposed to actually hurt you.
It's the opposite, my friends.