By Adam Harris-

(CBS) We have all heard it time and again: Use matchups to make start ’em, sit ’em decisions for your “on the fence players” in your lineup. I agree with this strategy but not early on in the season.

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Why? Because it’s hard to predict how good a defense will be early in the NFL season. Often the premature defensive projections will lead to the wrong lineup decision for owners across the fantasy world.

NFL defenses change drastically year by year. Just because a defense was bad at stopping the run last year doesn’t mean they will be this year. The NFL has turnover and parity unlike any other league, and therefore last year’s defensive results that create the illusion of a good matchup early on this year often can’t be relied upon.

For example, in 2012 the Pittsburgh Steelers were the best overall and best passing defense in the NFL. Last year, they finished 13th in overall defense and ninth against aerial attacks. Rounding out the top five pass defenses of 2012 were the Jets (second), Broncos (third), 49ers (fourth) and Cardinals (fifth). Last year, the top five pass defenses were the Seahawks (first), Saints (second), Texans (third), Bills (fourth) and Bengals (fifth). Not one top-five pass defense last year was in the top five the previous year.

The run defenses showed the same type of pattern. In 2012, the Buccaneers (first), Steelers (second), Broncos (third), 49ers (fourth) and Washington (fifth) had the best rushing defenses. Last year, it was the Cardinals (first), Panthers (second), Jets (third), 49ers (fourth) and Bengals (fifth). Only the 49ers produced back-to-back years in the top five against the run.

In fact, the 2012 Cardinals finished 28th against the run, increasing their run defense by 27 slots in just one offseason. The other big jumps from the top five include the Jets (who were 26th against the run in 2012 and climbed 24 slots last year), the Buccaneers (who dropped 17 slots against the run), the Saints (who were 31st against the pass in 2012, jumping 29 slots a year ago) and the Texans (who finished as the 13th best aerial defense in 2012, climbing 10 spots last season).

Perhaps the biggest example of my point, however, is the Chicago Bears. In 2012, the Bears were eighth against both the pass and the run, and we all know what happened last year here in Chicago. The Bears finished 15th against the pass and dead last against the run last year. That’s a huge slide.

Look at this year already. The Saints were the second-best pass defense last year, but they gave up 33 fantasy points to Atlanta quarterback Matt Ryan in Week 1. The Cleveland Browns had a stingy pass defense last year, ranking eighth, but after Week 1 the Browns are second-to-last after giving up 363 passing yards to Ben Roethlisberger and the Steelers. Obviously, one game isn’t enough to project the entire season, but it just shows you how unreliable last year’s defensive rankings are for fantasy owners trying to make lineup decisions minutes before kickoff.

My advice? Play your team as you meant to when you drafted it. You drafted a team with the idea of who was going to fill what slot and who was going to start, so stick with that. Don’t get too cute early on in the fantasy season. Give the NFL time to work its magic and show you the trends that will be your friend as the season goes on.

Worth a waiver?

Tuesday is waiver day to add new players. Here’s a list of guys worth looking at and my advice.

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DeAndre Hopkins (WR-HOU) — Available in 27 percent of Yahoo leagues

Verdict: Yes, he’s worth a waiver claim, especially in PPR leagues. He is too talented to not be a solid flex player.

Allen Hurns (WR-JAX) — Owned in 13 percent of Yahoo leagues

Verdict: Maybe, because Cecil Shorts III has hamstring issues. So while  Hurns will continue to see time, he’s not waiver worthy in 10-12 team leagues. The Eagles kept him quiet in the second half, and I imagine teams with a full game tape on him now will do the same.

Justin Forsett (RB-BAL) — Owned in 12 percent of Yahoo leagues

Verdict: Yes, because Ray Rice is gone and Bernard Pierce is bad. This job is up for grabs, and Forsett is going to get first crack at it. He’s definitely worth a waiver.

Isaiah Crowell (RB-CLE) — Owned in 3 percent of Yahoo leagues

Verdict: Maybe, because Ben Tate is injured and there’s no news on his status yet. Crowell saw the goal-line work last week and looked good in that role. If you have a spot open, go for it and claim him.

Terrance West (RB-CLE) – Owned in 39 percent of Yahoo leagues

Verdict: Maybe. I feel a little better about claiming West than Crowell. West saw 16 carries and took them for 100 yards. West is young, and Clevland is about youth.

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Adam Harris is a producer for 670 The Score. He co-hosts the Fantasy Nerd Herd every Friday night with Joe Ostrowski. Follow him on Twitter @aharris670 and feel free to ask fantasy questions.