Men have been trying to define commitment since the invention of stones and fire. Now we’ve come to learn that commitment means staying in and watching The Help on a Friday night.

For the Buffalo Bills, commitment means a contract that seems promising now, but it could become fatally flawed in the not-so-distant future. Earlier this morning Buffalo signed wide receiver Stevie Johnson to a five-year contract worth $35.25 million, with $19.5 million guaranteed. While Johnson’s speed is enticing, he was still inconsistent and had five games this year with less than 45 receiving yards.

Johnson will turn 26 prior to the start of next season, so there’s still room for growth. But at a yearly average of $7.25 million, his cap value is now above some of the league’s elite receivers. Johnson only barely cracked the 1,000-yard mark in 2011 (1,004), yet he’ll still be making significantly more than Greg Jennings in 2012, who’s only two years older and will be paid $3.89 million. Larry Fitzgerald is 28 too, and he’ll make $5 million next year.

This gives the Patriots an interesting, and possibly troubling option as the clock ticks down on the inevitable Wes Welker franchise tag before 4 p.m. ET. If Johnson has set the market and Welker will easily demand somewhere in the $10 million neighborhood yearly, why not just force him to play under the franchise tag for another year at $9.4 million?

The casual eye test between these two receivers tells us that Welker is the far superior talent. But since eye tests aren’t sufficient for the homer fan, the numbers observed by Ian Rapoport of the Boston Herald easily verify that belief:

Looking at Johnson’s career stats since 2008, he’s played in 48 games, caught 170 passes for 2,189 yards with 19 TDs. In that same span, Welker has played in 61 games, caught 542 passes for 4,930 yards with 23 TDs.  At age 25, Johnson, who falls in the category of a deep threat receiver, is five years younger than Welker.

There’s little doubt that Welker deserves to be paid much more handsomely than Johnson, and that Johnson’s deal will now solidify Welker’s asking price in that $10 million range. The problem for the Patriots lies in Rapoport’s last line, and that’s where the cozy relationship between Welker and New England’s brass could begin to deteriorate.

Welker will blow the candles out on his 31st birthday cake in May, and the wasteland of wide receivers is littered with elite stars who start to fade by their mid-30′s, sometimes abruptly. Randy Moss was 33 during his spiral that stopped at three NFL cities two years ago, and although he held on until he was 42, Jerry Rice only had three 1,000-yard seasons over his last eight years following his 34th birthday. Prior to that, Rice had strung together 11 straight years with at least 1,000 yards, averaging 1,404.4 yards per year.

With Welker commanding so much money regardless, forcing him to play one year under the franchise tag may be the wiser move, especially with a receiver who’s had a significant knee injury. Welker was second in receiving yards this year with 1,569 and easily first in receptions with 122, so the tag at $9.4 million would give the Patriots one more year to see if there’s any hint of a decline before making a commitment.

The chances of that actually happening are minimal, because Patriots owner Robert Kraft has little desire to alienate a key offensive cog, and possibly prompt a training camp holdout. That’s what happened last year when a similar franchise tag strategy was pursued with Logan Mankins. Tensions were raised, a holdout ensued, and eventually a long-term deal was reached (six years, $51 million).

But in a league where the veteran cliff is always unpredictable and lurking, the tag is designed for those who still fear commitment. Right now. that marriage could be just a little too risky for New England.