Let's look at the San Francisco 49ers. In 2007, they jumped at the chance to sign Clements from the Buffalo Bills. The Niners' deal with Clements was eight years for $80 million. And what did the Niners get? From 2006 to 2007, the opposition's passing yards went up (from 3,817 to 3,826), interceptions went down (from 14 to 12) and sacks went down (34 to 31). And that's with the NFL's defensive rookie of the year, linebacker Patrick Willis.

It's obvious what the Niners really needed -- a pass rush. That's why coach Mike Nolan persuaded his front office to sign defensive end Justin Smith from the Bengals. Did the Niners overpay for Smith, who had just two sacks last season? Maybe so. But they had no choice. You can cover all day, but if you can't rush the passer, you're not going to win in today's NFL.

Here's more evidence. In 2007, the Detroit Lions traded corner Dre' Bly to the Denver Broncos.

And what happened? The Broncos' pass defense promptly got worse. It surrendered more touchdown passes: 13 in 2006, 25 in 2007. Denver's interceptions went down (17 in 2006, 14 in 2007). So did sacks (35 in 2006, 33 in 2007).

In 2007, Indianapolis Colts president Bill Polian, who never gets enticed by free-agent seductions, let cornerback Jason David walk away. Another smart move by Polian. David was signed by the New Orleans Saints for four years, $16.5 million.

And, you guessed it, the New Orleans pass defense went downhill. The opposition passed for more yards: 3,122 in 2006 to 4,122 in 2007. Completion percentage was up: 56.3 in 2006 to 62.4 in 2007. Touchdown passes surrendered were up, too: 26 in 2006, 32 in 2007.

Why? Sacks were down. The Saints had just 32 sacks in 2007, after collecting 38 the year before David arrived.

What's more, in 2007, New Orleans allowed 15 pass plays of at least 40 yards -- tying the Baltimore Ravens for most in the league, according to Elias.