The Tennessee Titans have not really been what you could call a blitzing team. In 2009, they brought only 4 rushers 79.9% of the time, tops in the league. Surprisingly, that league-leading total was actually less than they rushed 4 in 2008, and the number of times they brought either 3 or 4 rushers fell from 83.3% to only 80.8%, or pretty much the same as the combined 80.7% they rushed 3 or 4 in 2007. With the Colts actually blitzing some in 2009, the Titans finally inherited the mantle as the league's most blitz-averse team.
The continuity in blitzing in 2009 may have been a bit of a mild surprise, as Chuck Cecil replaced Jim Schwartz as defensive coordinator. Cecil during his career as known as an aggressive player, and Fisher's Titans formerly (and nearly once again) employed the famously blitz-friendly Gregg Williams, whose Saints defense rushed 5 or more 47.3% of the time last year. Against the Cardinals, the Titans frequently brought more than 4 rushers, often with good results. That tendency to rush more than the basic 4 continues against Carolina, though with less impressive results. We'll have to see what the regular season brings, but in the interim, I thought I'd write a little more about blitzing.
More basic NFL math: 11 players on defense to guard against 11 players on offense. Of those 11 offensive players, potentially 6 (including a QB who lines up in shotgun) are eligible receivers. One of those has the ball, so the defense has to potentially account for 5 eligible receivers on any given play. That means the other 6 players are potentially free to rush the quarterback without worrying about any receivers at all.
Of course, teams can and do rush more than 6 players. All of those blitzes are at least theoretically unsound and may guarantee at least one open receiver. It doesn't always work out that way, as a big blitz often forces one or more of those eligible receivers, whether a tight end or one or more running backs, into blitz pickup mode to help protect the quarterback.
The goal of the blitz is generally to end up with a defender having a free run at the quarterback. There are two basic ways to do this: by bringing one more rusher than the offense has blockers, or by scheming pressure such that the offensive blockers can't block the defensive rushers. A good example of this latter type of schemed pressure is the overload blitz of the kind the Jets tormented Kerry Collins with in the Titans' loss last year.
Once you decide to bring a blitz, the next question is what kind of coverage you want to play behind the blitz. Man defense is always a popular option for coverage when blitzing. A quarterback who recognizes the blitz will be looking for his "hot" read, and man defense's closer coverage will generally be better at denying him his hot read than zone defense. Alternatively, teams can use a zone blitz. The Jets were the primary practitioners of this art last year, running a zone blitz on almost 15% of pass plays against, tops in the league. In the zone blitz, the defenders on side opposite the overload, including the defensive end and the outside linebacker may drop off into coverage. For more on the zone blitz, see this piece by the invaluable Chris Brown. The Titans aren't completely unfamiliar with the zone blitz, as they did run it 1.4% of the time last year, but they were mostly unfamiliar with it, as they did it less often than any other team. I will therefore concentrate on man blitzes.
Like the Dungy-era Colts, the Titans do like to play a lot of coverage with at least one, and generally two, safeties playing over the top, either as part of a Cover-2 zone defense or part of a simple man-2 scheme. When you blitz, though, you lose your those deep safeties and end up playing Cover-0. Once again, see Chris Brown, namely the first diagram in this other piece.
We've seen Cover-0 alignments a couple times on here before. In the above-linked breakdown of the endgame against the Jets, the Titans' final offensive play was against Cover-0. We've seen the Titans run Cover-0 in the preseason.
Alas, the Mike Williams touchdown play was a great example of the weaknesses of Cover-0. A brief refresher: the Seahawks faced a 3rd and 1 at their own 49 midway through the second quarter. With Charlie Whitehurst at QB, they had two tight ends, one on each end of the line of scrimmage, and one wideout to each side with a lone setback. The Titans were in their base 4-3 personnel, with Donnie Nickey and Myron Rolle the safeties. Both outside linebackers were lined up on the line of scrimmage outside the tight ends. Nickey and Rolle were both lined up over a tight end, about 3 yards off the line of scrimmage. The Titans were in what looked like a clear Cover-0 set, with cornerbacks McCourty and Mouton playing 7 and 5 yards off their respective receiver.
Two ways to set up your cornerbacks in this alignment: playing tight up against the line of scrimmage, or playing off like Mouton and McCourty did. The downside of playing off is it's easier for the quarterback to make and complete an immediate throw on a smoke route. The downside of playing close is, if the cornerback misses the jam on the receiver, it's probably a touchdown (for a good example, see Andre Johnson v. Nick Harper, Week 2, 2009). The Titans tend to favor strong tacklers at corner and are probably better served by playing off. Alas, Ryan Mouton shows what happens when you miss your tackle in a Cover-0 defense. He took a bad angle to Mike Williams, Williams made a move, and there was nobody back on defense to prevent the touchdown. Cover-0 is like that: a single point of failure can result in a score against you.
Fast-forward one week, to the Titans' second preseason game against the Cardinals. On their second drive of the game, not quite 6 minutes in, the Cardinals faced 3rd and 16. Matt Leinart lined up in the shotgun with Tim Hightower to his left, while three eligible receivers, including TE Steven Spach, standing up to his right, and one lined up to his left. The Titans were in their nickel personnel, with Fuller lined up inside the slot receiver. As the play clock wound down, Witherspoon, Tulloch, and Fuller all approached the line of scrimmage, showing blitz. Of those three, Witherspoon and Fuller actually did blitz, while Tulloch initially showed blitz but didn't, spying Hightower to see if he dropped off for a pass. The other four defenders are well off the line of scrimmage, and three aren't even visible on the screen. Leinart successfully read the blitz and found Spach running an angle route. Unlike last week, Hope came up and made a very solid tackle to stop Spach well short of the first down.
ESPN shows us a better replay of the coverage, and the Titans safeties had lined up in their normal 2-deep look. As soon as the ball was snapped, Hope rotated over from the offensive left to cover Spach on the other side of the field. If the Titans do want to run more blitzes out of Cover-0, it will probably out of this disguised 2-deep shell and not the obvious Cover-0 Seattle exploited for the touchdown. It's also instructive to point out Seattle's score against Cover-0 came in 3&1, a much more favorable down-and-distance situation than the 3&16 Arizona faced.
A third preseason game, a third example of Cover-0. Carolina faced 2&2 at midfield in the two minute drill at the end of the first half-with 1:29 remaining, to be specific. Like Leinart, Moore was in the shotgun with a line setback, while the Panthers had a balanced formation with a slot receiver (TE Barnidge, WR Guy) lined up a couple yards outside the offensive tackles and a receiver outside each set of numbers. The Titans were showing their 2-deep look with the corners playing well off the outside receivers, while all 7 other defenders were within 3 yards of the line of scrimmage. It looked like an obvious blitz and indeed was, as RB Goodson stayed in to block. With 6 to block 7, Moore found his hot receiver, WR Guy running a quick in-breaking route toward the middle of the field. Griffin had Guy in man coverage, but appeared to take an angle too far to the outside of the field. Guy's route, though, was right toward Chris Hope, who had been in coverage in Barnidge. As he'd done the week before, Hope made a sure tackle and limited Guy to an 8 yard pickup.
There are a couple other teaching points I could take out of this last play, and some broader lessons I could draw. The foremost of those is with these risky defensive calls, you can see why the Titans place such a big emphasis on tackling ability in the secondary. You normally think of it more on run plays (and I know that in this I completely ignored run blitzes), but it's just as important, if not more so, in several passing situations. I'm hesitant to say these things will mean much, if anything, when the regular season comes, but it might, especially between they've run it out of different looks. Still, if you have something in the gameplan (and honestly, hitting rush lanes and playing man behind it isn't rocket science), it probably doesn't hurt to get it on the table and let opposing quarterbacks think about it even if you never plan to run it again.
*-Rusher numbers taken from Football Outsiders Almanac/Pro Football Prospectus for the relevant year. For all years mentioned, I was the primary Titans game charter, probably producing on average 55-60% of the Titans data. Several links to Chris Brown, just because he has great and easy to find explanations of the stuff I mention, and he knows this stuff much better than I do.