It never fails. The NFL schedule gets released and the instant analysis begins.

"That's just a brutal stretch for Team A!"

"Can you believe how easy Team B's schedule is?"

"Team C had better start quick because they'll be lucky to go .500 after the bye!"

For fantasy football, where the minutiae of statistics are usually gold, the kvetching is even louder.

"Draft Player X! Look how easy his schedule is!"

"Stay away from Player Y! What a brutal schedule against the run!"

"Be ready to trade Player Z after Week 10! His fantasy playoff schedule is horrible!"

The idea that we can look at an NFL team's schedule and decide -- months in advance -- whether or not it's favorable or unfavorable is dubious at best. For heaven's sake, this is pro football, and maybe the least predictable sports league in existence. There are "out-of-nowhere" contenders and sliders every year. The San Francisco 49ers' Las Vegas over/under win total heading into 2011 was 7.5. (They won 13.) The Tampa Bay Buccaneers' over/under was 8. (They won four.) Heck, overall, the Vegas over/under line was off by at least two wins for a whopping 14 of 32 teams (44 percent), and missed by four wins or more in five separate cases.

Now take this one step further, to fantasy. Not only do we have a difficult time predicting which teams will be good, now we also have to promise which players will dominate for those teams? If you had been able to look into your crystal ball and predict those 13 Niners wins, I'm fairly sure I would've told you that Frank Gore would come close to being fantasy's MVP for 2011. Instead, he finished tied for 13th in fantasy points among RBs. If you'd told me the St. Louis Rams were going to win only two games, I'd have felt sure that Steven Jackson would be utterly ineffective and probably injured, but in fact he finished 10th among RBs, ahead of Gore. This isn't to say trying to determine relative value among players is a fruitless pursuit; in fact, it's something I spend much of my professional life thinking about. But I have a hard enough time evaluating the teams and players themselves, figuring out usage patterns and skill sets. Now I have to inject the noise of which NFL teams are going to be toughest and easiest to play against?

To do that here in April, long before the season starts, is to ignore the possibility of player movement that may occur over the summer, via free agency or trades. It ignores the possibility (nay likelihood) of injuries that can significantly affect how a team performs or even how it approaches the game. It also ignores the pure randomness that is such a large part of a league where what separates "good" teams from "bad" ones is paper-thin.

Specifically, of course, we're talking about defenses. Which defenses will be easiest to run against, throw against, score against? Which defenses will represent bad matchups? My answer: For the most part, we can't predict this.

Do some defensive themes repeat from year to year? Of course they do. In each of the past six seasons, the Baltimore Ravens have ranked in the top five in rushing yards allowed. It's plainly a point of emphasis and an area of strength for the Ravens. The Oakland Raiders have numbered among the six worst rush defenses (in terms of yards allowed) in each of the past five seasons. It's obviously a serious problem that the team hasn't yet solved. But in a league where teams make massive improvements and/or steep declines in the span of a single year, these examples are much more exception than rule.

But qualitative logic apparently isn't enough to rid the fantasy world of these insidious preseason crutch arguments. So let's break it down. I'll look at three defensive categories over the past several years, and focus on how repeatable or unrepeatable defensive performance is on a season-by-season basis.

Actual Points Allowed

If you could accurately predict which defenses will allow the most overall points in the 2012 NFL season, you'd be well on your way toward figuring out which fantasy players have the most favorable schedules. But how does one conjure up such a prediction? Most folks do what's easy: They look at last year's performance. The Pittsburgh Steelers, 49ers, Ravens and Houston Texans were the four stingiest defenses to score against last year, so (goes the logic) they're defenses to keep your fantasy studs away from this year.

Great, except the Texans, who allowed only 17.4 points per game in '11, allowed a ridiculous 26.7 ppg in '10, which was 29th in the league. The 49ers allowed only 14.3 ppg in '11 -- just a fraction from being the best scoring D in the NFL -- and gave up 21.6 (which ranked 16th) in '10. Going the other way, the Green Bay Packers had the No. 2 scoring defense in the league in '10, and were No. 19 last year.

Last year alone, 10 of the league's 32 defenses (31 percent) saw their points allowed change by five or more points per game:

Points Allowed fluctuation, 2010 versus 2011

And this isn't an uncommon occurrence: It's happened 37 times in the past five seasons. Perhaps most unnerving is the fact that it isn't the same teams flip-flopping back and forth between high and low points-allowed totals. In fact, 25 different franchises have seen their points allowed per game increase or decrease by five or more points in at least one of the past five seasons. Five points may sound a bit arbitrary (and it is), but when you consider that the average NFL defense allowed 22.2 points per game last year, five points (or 22.5 percent) is a rather huge fluctuation.

Yards Allowed

"Fine," you say. "It's tough to predict which defenses will give up a bunch of points based on last year, but I don't care about points nearly as much as I do about yards. Scoring may come and go, but if I remember a defense getting marched up and down the field last year, they're sure to get marched up and down the field this year, too!"

Incorrect.

Let's start with run defense. As I mentioned earlier, there are a few run defenses that have remained steady (for good or bad) over the past six seasons. Exactly four franchises have featured defenses that have ranked either in the top 10 or the bottom 10 in rush yards allowed in that span; the Ravens and Steelers have stayed in the top 10, while the Raiders and Cleveland Browns have remained in the bottom 10. Heck, if we want to get charitable, and make our window the past three years, we can add the 49ers and Atlanta Falcons on the strong side, and the Buccaneers, Detroit Lions, Buffalo Bills and Indianapolis Colts on the weak side. How many of those 10 squads do you think will stay in the "extremely tough to run against" or "extremely easy to run against" column in 2012? All of them?

The 2011 Jacksonville Jaguars and New York Jets don't believe so. Coming into the '11 season, the Jets were known for their run-stopping ferocity, while the Jags were lousy against the run. You were supposed to be way better off if your fantasy RB was playing the Jaguars, right?

Rushing Yards Allowed, 2008-11

Whoops. And anyone who's played even one season of fantasy football knows that even those fabled Steelers and Ravens defenses, while stout against the run, can be had. Heck, last year Ray Rice and Arian Foster put up huge days against the Steelers, while Marshawn Lynch and Ryan Mathews did numbers on the Ravens. Put it this way: Hesitating to draft Cedric Benson and/or Peyton Hillis last year turned out to be a smart move, but it wasn't because each had to play the Steelers and Ravens twice.

Just look at these roller-coaster NFL run defenses over the past several years:

Rushing Yards Allowed, 2007-11

For me, the huge variability here makes this stat untrustworthy as a predictor.

And the story is less reassuring when it comes to pass yards allowed. In that category, wild season-to-season swings seem more like the norm than the exception. No NFL team has ranked exclusively in the top 10 or bottom 10 of pass yards allowed during the past six years (or, for that matter, the past four years). If we limit our scope to the past three seasons, there is exactly one team that's been either consistently good or consistently bad defending the pass: the Jets. Does this mean you can think twice on occasion when your fantasy wideout has to visit Revis Island? It does. Should that be enough to make you not draft that wideout in the first place? No way. There's just not enough statistical pattern against any other opponent for strength of schedule to matter.

No matter how you slice the pass defense numbers, they're alarming. Look at last year's complete top 10, and how they fared in the previous four years:

Passing Yards Allowed, 2007-11

Up and down and up and down. Is there anything here that should make a fantasy owner think, "Clearly, I have to avoid drafting this QB or WR, because they play Team X"? I say no.

Fantasy Points Allowed

"All right," you say. "Enough with these season-long counting stats which don't actually impact my fantasy bottom line. I'm going to go strictly by what really matters: How many fantasy points a defense allows to a particular position."

In general, my instinct tells me that fantasy points allowed would actually be a less reliably predictive stat, because as anyone who's ever lost their fantasy championship game to Aunt Hilda (who drafts her team based on player handsomeness) can tell you, fantasy points are sometimes pretty random. Touchdowns -- a primary source of fantasy points -- are extremely difficult to project on a week-to-week basis. For instance, if a defense allows LeSean McCoy to amass 98 yards on a particular drive, but then Jeremy Maclin catches a 1-yard TD, well, the fantasy points amassed are misleading.

But let's look at the repeatability of fantasy points allowed anyway. Here were last year's top five and bottom five defenses in fantasy points allowed to QBs, and how they each fared in those categories in the past five seasons:

Fantasy Points Allowed to Quarterbacks, 2007-11

Look at the Texans! Could I have analyzed the Texans acquiring Johnathan Joseph to play corner and installing Wade Phillips as defensive coordinator, and assumed some improvement in the team's play against the pass? Sure. But could I have drafted trying to avoid the Texans' secondary? Because they were literally the worst pass defense in football in '10, I could not. Heck, look at the Jets for heaven's sake! We just established that the Jets don't give up many passing yards, yet they somehow stunk against fantasy QBs in '10, and then bounced back in '11. And going the other way, I don't think you'd have relished playing your passing-game fantasy players against the Packers or Bucs entering the '11 season, but each turned out to be a sweet opponent.

Here's the same chart for running backs:

Fantasy Points Allowed to Running Backs 2007-11

There's more consistency here for sure. The Texans again stand out for being an unpredictable success, this time versus the run, whereas only the Rams stand out as being unexpectedly terrible. But looking at the rest of the data, there's still scads of jumping around. The Jaguars have gone from 20th to ninth to 24th to eighth in this category over the past four years. The Cardinals have gone from 22nd to 17th to 31st to 10th. And if that keeps happening, team after team, year after year I just don't think we know enough in April to start downgrading (or upgrading) fantasy rushers based on opponents.

Finally, even if we accept that this is one area that looks more predictive than others -- that we might be able to assume something about the better run defenses from last year, and predict that they'll be pretty good again this year -- we still might be doing ourselves a disservice. If we look back to the '11 season, the rusher who faced the roughest slate of opposing defenses according to the top 10 in fantasy points allowed to RBs (and who stayed healthy all year) might've been Ray Rice. He had two games against the Steelers, one against the 49ers, one against the Cardinals and one against the Texans. And he had a pretty good year.

Conclusions

I'm not saying fantasy schedules don't matter. Of course they do, very much. I'm merely contending that more often than not, we're flat-out wrong about which defenses represent good matchups before the season begins, because last year's numbers often don't apply this year. There are a few carryovers, yes. You might fret just a touch if your prospective fantasy RB has to face the Steelers and/or Ravens, but then again, those units are beginning to age in a major way. Can I promise this isn't the year a cap-strapped Pittsburgh D -- whose starting defensive line from last year is the oldest in the league and is coming off major injuries -- will fall off the table? I cannot.

Once we've actually seen the 2012 versions of NFL defenses, absolutely, I'll be all aboard the defensive-evaluation bandwagon, writing about what I actually observe. And in-season data is extraordinarily helpful. By the time November rolls around, looking at fantasy playoff schedules will be good for business.

But don't bother now. Draft good players, and adjust to opponents later.