Michael Perez/Associated Press

Back in April, when fans of both the Philadelphia Eagles and Washington Redskins were trying to make sense of the sudden and stunning developments that saw Pro Bowl receiver DeSean Jackson jump within the NFC East from the former franchise to the latter, CSN Philly's Reuben Frank noted in a column that Jackson tends to tail off as seasons wear on.

It might be that Jackson's 5'10", 178-pound frame becomes less reliable and more vulnerable with each hit he takes, or it might be that a finesse receiver such as Jackson simply can't consistently reach his full potential in colder temperatures.

Whatever it is, there's something to it.

ESPN's John Keim wrote last week that 10 of Jackson's 20 career 100-yard games have come in September. And although he's had some good late-season stretches in his career, a look at the 27-year-old's combined monthly numbers from the last three seasons indicates that he does seem to fade as winter approaches and arrives.

DeSean Jackson: Month-by-month splits, 2011-2013 Month Games REC/game YDS/game YPC TD/game September 11 4.6 79.9 17.2 0.36 October 11 5.0 73.2 14.6 0.36 November 10 3.6 65.5 18.2 0.30 Dec/Jan 11 4.2 63.4 15.2 0.36 Pro Football Reference

There's a real clear split between September/October and the rest of the year. And while colder temperatures certainly have a dulling effect on offensive players league-wide, especially when it comes to the passing game, the fact is that Jackson's starting partner hasn't experienced the same drop-off.

Jeremy Maclin: Month-by-month splits, 2009-2012 Month Games REC/game YDS/game YPC TD/game September (12) 12 3.8 48.2 12.8 0.67 October (14) 14 4.9 71.2 14.4 0.50 November (15) 15 4.4 58.9 12.6 0.33 Dec/Jan (20) 20 4.4 62.7 14.4 0.35 Pro Football Reference

To determine if indeed this is weather-related, we looked at the kickoff temperatures for every outdoor game of Jackson's career and compared colder games with games played in comfortable conditions or in domes.

If we used 50 degrees Fahrenheit as our divider, the broad numbers from Jackson's first six years in this league actually indicate he's perfectly comfortable in cold conditions.

DeSean Jackson: Six-year career based on temperature Temperature REC/game YDS/game YPC TD/game Above 50 degrees 4.1 73.9 17.8 0.37 Below 50 degrees 4.1 60.8 14.8 0.37 Pro Football Reference

So he picks up an extra 13 yards per game. Big whoop. But dig a little deeper, and you'll notice that Jackson was actually really strong in cold weather during his first two seasons.

DeSean Jackson: 2008-2009, based on temperature Temperature REC/game YDS/game YPC TD/game Above 50 degrees 3.6 61.7 17.0 0.27 Below 50 degrees 5.0 80.2 16.0 0.56 Pro Football Reference

That has skewed the current numbers. If we're just looking at what he's done for the Eagles lately in cold-weather games, it becomes more obvious that he's been having trouble when the temperatures dip into the 30s or 40s.

DeSean Jackson: 2010-2013, based on temperature Temperature REC/game YDS/game YPC TD/game Above 50 degrees 4.4 80.1 18.2 0.42 Below 50 degrees 3.3 43.4 13.2 0.20 Pro Football Refernece

What the hell happened? In the 11 cold-weather games Jackson has started since 2010, he's gone over 60 yards just once and has just two touchdowns. He's been held to 36 or fewer yards seven out of 11 times. That's something that has happened to him only 12 times in the 45 other games he's played during that stretch.

Jackson has hit the 100-yard mark 13 times in 45 non-cold-weather games the last four years. And he's 0-for-11 in that respect when temperatures drop below 50 degrees.

To be fair, let's again compare those totals to Maclin.

Jeremy Maclin: Career based on temperature Temperature REC/game YDS/game YPC TD/game Above 50 degrees 4.3 58.7 13.5 0.49 Below 50 degrees 5.3 67.8 12.9 0.33 Pro Football Reference

Maclin, who is playing for the same team in the same games, has seen his touchdown rate drop in the cold, but nothing else sinks. In fact, he has averaged an extra catch and nine extra yards in games in which the temperature is 50 degrees or lower.

OK, 45 degrees isn't exactly freezing, so maybe this is a fluke. After all, the sample sizes for these cold-weather games aren't huge. But what if we drop the cutoff point to 40 degrees? Basically, let's keep that recent four-year sample but separate games in which it was basically freezing.

DeSean Jackson: 2010-2013, based on temperature Temperature REC/game YDS/game YPC TD/game Above 40 degrees 4.3 76.2 17.7 0.39 Below 40 degrees 3.0 38.3 12.8 0.25 Pro Football Reference

The gap is even larger. His yardage numbers are almost 100 percent better in non-freezing games than they are in borderline-freezing games.

In 2011, he faced the Cowboys, Seahawks and Jets within an eight-week stretch, and the average temperature for those three games was 38.3 degrees. Jackson had a total of nine catches for 93 yards and zero touchdowns in those games. That's become all too common.

Although, it should be noted that Jackson had a relatively solid four catches for 59 yards and a touchdown in a 27-degree home game against the Lions this past December. That was his best really cold game since he put up six catches, 140 yards and a touchdown in a 32-degree home game against the 49ers in December of 2009.

And again, offenses stall in general when things get that frigid, but Maclin has survived.

Jeremy Maclin: Career based on temperature Temperature REC/game YDS/game YPC TD/game Above 40 degrees 4.3 57.7 13.4 0.45 Below 40 degrees 6.0 79.4 13.2 0.40 Pro Football Reference

Throw in that Jackson has averaged just 3.2 catches for 53.5 yards in six playoff games, and I think there's reason to doubt his ability to rise to the occasion when the elements become a factor and his body has been worn down late in the year.

The fact that he missed the final five games of the 2012 campaign and was banged up at the conclusion of the 2010 season won't help his case against those who believe he can't handle that cold, late-season grind.

That's something Redskins fans should fear, especially considering that Jackson and his teammates will spend the entire month of December outdoors in the cold (three home games and one trip to New York to play the Giants).

In the meantime, the 'Skins would be smart to keep their top receiver as fresh as possible, because while it is ever so slightly warmer in D.C. than it is in Philly, that alone might not be enough to save Jackson this winter.

Brad Gagnon has covered the NFC East for Bleacher Report since 2012.

Follow @Brad_Gagnon