assuming I want to hit fourth (I'd celebrate with a third-place finish), should I try to finish fifth or sixth place in every category? In vanilla AL- and NL-only leagues, what numbers do I need to reach to finish in the top half of AVG, RBI, ERA, etc.?Since the second part of the question is easier to answer, I'll start there.
Last year, in the CBS Sportsline expert A.L., you would have needed 75 points to finish in 4th. To finish 5th in each category, you would have needed to hit .273/199 HR/880 Runs/872 RBI/108 SB. On the pitching side, you would have needed a 82 wins/48 saves/985 K/4.10 ERA/1.33 WHIP.
In the N.L., 76 points would have put you in 4th, and you would have needed the following: .2732/206/857/839/124 on offense, with 74/57/1014/4.05/1.32.
You'd want to do a more thorough analysis of your own league than what I just did. Depending on whether or not your league is a carryover league or not, there might be a wider gap between the top teams and the bottom teams across the board. Carryover leagues tend to find more teams tossing their top players aside to grab next-year talent, so the chasm between first and last in a category tends to be slightly wider. More importantly, there's usually a big gap somewhere between 6th and 7th or 7th and 8th in a category.
The first part of your question is more important, though.
I always shoot for first place, though I understand why you're asking this question. Often in long-term freeze leagues, one or two teams has a stacked freeze list and it doesn't feel like you have a fighting chance.
If this is the case, it's probably better to play aggressively to win six or seven categories (in 4x4) or eight or nine categories (in 5x5) than to try and be above average in all eight. Your resources are limited; spreading a little money across all categories typically results in a 6th or 7th place team as opposed to a money team. Of course, you might get lucky and finish 4th, but you could just as easily be unlucky and finish 10th. An across-the-board strategy tends to have a great deal of variability built into the plan.
Saves and steals are the most obvious categories to toss aside, simply because you can make up ground here later if you get lucky and grab a cheap set-up guy in April who winds up saving 25-30 games, or a cheap $1 back-up who steals 30 bases off of the bench. If you're strong across all of the other categories, keep in mind that you don't need to finish with 8 points in SB or saves. Finishing with three or four points will do nicely.
You still might not win this way (in fact, in dump leagues you probably won't) but I think you've got a better chance of being competitive by not spending your money in one or two categories and maximizing your dollars in the other six or eight categories. It's worked much better for me than spreading my dough across the board ever has.