This is not the time to pull a Leon Lett and have a brain cramp when making out your starting fantasy lineups for the rest of the football season. Fantasy owners cannot afford to make any mistakes from here on out. If you insert an injured player into your lineup and he does not dress for his game, that big fat zero he puts up for your fantasy squad could be the death knell for your team’s title dreams.

You do not want to be the runner-up in your league’s Super Bowl or the bubble team left out of the playoffs because you used a running back with a bum hamstring or a kicker kicking in 60-mph winds. Here are the four determining factors for picking the perfect lineup for your fantasy football team:

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(1) Schedule

This is as much of a no-brainer as it is to kneel on the ball when you have a two-touchdown lead and 30 seconds remaining. The first determining factor for your lineup decisions, especially the ones where you do not know whom to pick between two equally valued players, should be which player has the more advantageous matchup.

The Denver Broncos have arguably the best defense in the NFL. They have the best pass rush and the best cover corners in the league. But they face the New England Patriots (sixth-ranked offense) in Week 15, a week where fantasy playoff games and league championship matchups will be decided.

While the Broncos lead the league in sacks, are ranked in the top-10 in fumble recoveries and interceptions, and are fourth in total defense, would you use their defense against Tom Brady when your fantasy team’s title hopes hang in the balance?  I wouldn’t unless my other choices were the Cleveland Browns and the Texas Tech Red Raiders defenses.

But matchups make things real interesting for fantasy owners. Drew Brees should always be started in my mind, but three weeks ago he was up against the seventh-ranked Los Angeles Rams pass defense, so maybe some fantasy owners went with the other quarterback on their rosters instead…and then proceeded to suffer from ulcers and sleepless nights after Brees had a five-touchdown afternoon.

Then the last two weeks, probably all Brees owners across the fantasy galaxy started Brees against Tampa Bay's 16th and Detroit’s 20^th-ranked pass defenses (and rightly so) and watched him throw six interceptions without a single TD pass. Now, Brees had averaged 340 passing yards and had eight touchdown passes the past three times he faced Detroit heading into their most recent game, so with that in particular it proves that when fantasy owners play the percentages with matchups they may occasionally get screwed over. But if you factor the matchup into every decision, it will pay off for you more times than not.

Nobody knows the players on your fantasy roster better than you do, but checking the home-away splits, past successes/failures against opponents in recent years and the rankings of the defenses your players are about to face is necessary. The owners in your leagues who devote the most time to studying those numbers during the regular season are likely the ones qualifying for the playoffs. For them, they know the drill. They also know that now they even have to put in more work to pick the perfect playoff lineups.

(2) Weather

It is time to start paying more attention to the Weather Channel on the weekend and less attention to your significant other. Mother Nature is going to play a big role in your fantasy games from here on out, especially when the guys in your lineup are playing in wind, snow, rain, and cold. Winter is closer than Richard Sherman is to opposing receivers.

You may choose to bench your normal starting quarterback if he is slated to throw in 50-mph winds, while you may be more apt to use a defense scheduled to play in the middle of a turnover-prone snowstorm. The weather can be a huge deciding factor when choosing between two skilled position players, kickers, or defenses. Ignoring the weather when filling out your lineup from here on out would be dumb as dropping Aaron Rodgers for Charlie Whitehurst this week. Before you get too comfy with the newspaper on Sunday mornings, turn on your computer and check the weather conditions for your players’ games.

(3) Injuries

This should not be news. Fantasy football owners look at injury reports more often than they look at their monthly bills and their kids’ report cards combined. If a fantasy owner uses a player who does not suit up and posts a big fat zero in the points column, not only will they be the laughingstock of their league, they could cost themselves hundreds of dollars and the chance to hoist the league championship trophy over their heads at the end of the season.

The word “questionable” is the worst word a fantasy owner can hear. Fantasy owners know they will have to monitor their players with that label on the injury report all week right up until kickoff. But this late in the season when your fantasy games are crucial, you must pay close attention to the players listed as “probable” or “doubtful” on your roster, too. You never know when a probable player may suffer a Saturday setback or when a doubtful player eats that Slim Jim that suddenly makes him healthy enough to play at the last minute.

This is not the time of the season to set your lineup on Saturday night and then go out first thing Sunday morning for a day-long event. You have to check for updates on Sunday morning to see if a pre-game hangnail or a dress code violation may bench someone you penciled in for starting. In this age of electronic devices, you have no excuse to not make sure your lineup is good to go before the 1:00 pm kickoffs.

(4) Role

If you have a running back who splits time and shares carries with another back on his team, your guy is not going to be as valuable fantasy-wise as the workhorse who stays on the field for 90 percent of his teams plays and monopolizes all of the opportunities to rack up yards and touchdowns.

Why is Dallas’ Ezekiel Elliot having such a monster year?  It is not just because he runs behind the best offensive line in the league. It is because he is given the ball an inordinate amount of times. He does not lose carries to a Tevin Coleman-type backup like Devonta Freeman does in Atlanta.

When choosing between two players, using carries, pass attempts, touches, and targets as determining factors is another shred of evidence to take under consideration. Just like plate appearances is the most underrated stat in fantasy baseball, because the more plate appearances a hitter gets the more chances he has to hit home runs and steal bases, football players can produce more yards and score more touchdowns when given extra opportunities. It is fantasy math and is easier to understand than any of Pittsburgh’s complex offensive sets.

If you need any more help picking the perfect lineup to help your fantasy squad advance to the playoffs and eventually your league’s championship game, find your favorite quarter, flip it better than Clete Blakeman and go with whomever the coin tells you to go with.