It used to be that when an NFL scout or coach described a defensive prospect as a "tweener," you knew what he was really saying was, "He's a bad fit."

Not quite big enough to play end. Maybe just a little too large for outside linebacker.

You knew that the player would be a late-round draft pick, if he were drafted at all. And if he did end up in a team's training camp, he would be the longest of long shots -- unless he did an exceptional job on special teams.

Now, "tweener" has an entirely different connotation. Now, for many NFL clubs, a defender whose physical traits don't allow him to fall into a specific positional category can actually be an ideal fit.

Tweener isn't even the label that such a player wears. It has been replaced by "hybrid."

This is what it means: He can rush the quarterback or play the run with a hand down, just as an end would; he can do the same standing up, just as an outside linebacker would; he can drop into coverage from the end or linebacker spots. And he is blessed with the combination of size, strength, and blazing speed to do all of these things exceptionally well.

A hybrid can play in a 3-4 or 4-3 scheme, and usually ends up working in multiple fronts because no defense goes an entire game in a single alignment. Besides versatility, he brings a crucial dimension to the never-ending strategic warfare between offensive and defensive coordinators: His presence makes it extremely difficult for a quarterback to read the defense. That's because, before the snap, the hybrid figuratively "hides." Regardless of whether he has a hand down or is standing, the offense has no clue as to what he will do after the snap because he will almost always show one thing and do another.

And there is no consistent pattern to where he will be. On one snap, he could be in a three-point stance. On the next, he could be standing on the outside across from the tight end, preparing to cover him on a pass route. On yet another snap, he could be standing away from the line, in the traditional area that a linebacker stands, ready to rush or drop into coverage. And there is always a chance he will end up in the middle of the defensive line, as part of an even-front look, looking to try and overpower the center.

"Years ago, calling a player a 'tweener' was a bad word," Ravens outside linebackers coach Mike Pettine said. "But we like the hybrid type …" So do many other teams around the league.

Hybrid defenders have become so valuable that three were among the top 10 picks of last April's draft -- Chris Long, second overall by the St. Louis Rams; Vernon Gholston, sixth overall by the New York Jets, and Derrick Harvey, eighth overall by the Jacksonville Jaguars. Although neither Long nor Gholston has been particularly impressive in the preseason and Harvey was a holdout, there are plenty of examples of players who have thrived as ends/linebackers.

Among them are San Diego's Shawne Merriman, Dallas' DeMarcus Ware, Arizona's Travis LaBoy, Baltimore's Terrell Suggs, and New England's Adalius Thomas and Mike Vrabel.

As far as Patriots inside linebacker Tedy Bruschi is concerned, Vrabel is the consummate hybrid (besides playing outside linebacker, end, and inside linebacker, he also takes snaps at tight end in goal-line situations and has caught eight career touchdown passes).

"It's one thing to have the ability to do it, which he does," Bruschi said. "But you've got to know what to do once you switch positions. Vrabel knows the entire defense inside and out. That's probably the biggest compliment I can give him. Ask him what a safety does on a particular coverage, and he'll tell you that … and he'll throw in what the strong-side corner does too."

"It's not like he's just a utility infielder," Patriots coach Bill Belichick said of Vrabel. "I think he actually plays his position very well when he just has to play the one spot. Not that he has (just) one spot, but ... as an outside linebacker."

Thanks to Suggs, the hybrid role actually received its own salary classification within the league's franchise-tag structure. That was the compromise the Ravens and Suggs reached after a dispute over the type of position tag, and compensation, he should receive. In February, the team placed a linebacker franchise tag on Suggs with a one-year tender worth $8.065 million, the average of the five highest-paid linebackers in the NFL. In March, he filed a grievance, saying he was entitled to a one-year tag of $8.879 million for defensive ends because he played more than half his snaps at that position. Then, earlier this month, the Ravens and Suggs agreed to a one-year tender worth $8.47 million, a number designed to fall in the middle of end and linebacker … just as a hybrid does.

Suggs' five seasons in the NFL reflect the completeness that is commonly found in a hybrid. Since joining the Ravens as the 10th overall pick in 2003, he has had 45 sacks and made two Pro Bowl appearances. Although Suggs had a career-low five sacks last season, he had a career-best 80 tackles, proving that he can be just as effective stopping the run as he is rushing the quarterback.

An outside linebacker who specialized in rushing the passer and who would periodically put a hand on the ground was once called an "elephant," which got its name from the first letters of end and linebacker. It was a role that caught on in the 1980s and continued to be popular in the '90s because of the success that the San Francisco 49ers had with Charles Haley and the then-Los Angeles Rams, Pittsburgh Steelers, and Carolina Panthers had with Kevin Greene.

The biggest difference between an elephant and a hybrid is that a hybrid's first responsibility isn't necessarily to rush the passer. Instead, he could drop into coverage just as easily as goes after the quarterback, making it easier to disguise coverages.

Depending on the team, the hybrid goes by different nicknames. In New England, he is called a "Joker." In Arizona, he is called a "Predator." The Miami Dolphins used to refer to the position as the "Jack," as in "jack of all trades."

Jason Taylor, whom the Dolphins traded to the Washington Redskins last month, proudly wore the "Jack" title during his time in Miami. By effectively filling multiple roles, he was able to have the best of his 11 seasons in 2006. He registered 62 tackles, including 13.5 sacks. He also forced 10 fumbles, deflected 11 passes and had two interceptions on the way to becoming the NFL's Defensive Player of the Year.

"It's so much better than being just a D-lineman," said Taylor, who was a linebacker at the University of Akron and spent the bulk of his career as an end. "I like to think you have to be the most athletic person on the field. I'm not throwing rocks at the other players, or other positions, but to be the jack you have so much to do.

"You have to do everything. There's adjustments. There are calls. You have to make instant reads and then react."

For offenses, there is even more to do in trying to make sure the hybrid doesn't become a disruptive force. Most of it is guesswork that, depending on the talent of the hybrid, can occupy a large chunk of an offensive coordinator's time in preparing for an opponent.

Ravens offensive coordinator Cam Cameron understands the magnitude of the challenge.

"It's one of those unique guys you have to account for every time," Cameron said. "He might be over here, he might be over there, back there. And if he's (on the quarterback's blindside), you better make sure you have two guys on him because he's going to hit you right in the back.

"Now, looking over and knowing where he is is one thing. Blocking him is another."

Harvey's 33-day holdout -- which finally ended on Wednesday -- figures to do severe damage to his ability to make a significant impact as a rookie. That's a shame, considering the potential he has to contribute as both a pass-rusher and in pass coverage.

"I think he did what we asked him to do, drop sometimes, but I think his strength is (with) his hand down," said Urban Meyer, Harvey's coach at Florida. "Those guys are hard to find."

Ware might be one of the best examples of the type of impact a hybrid can make. He already has made the Pro Bowl twice in three NFL seasons. He has been particularly effective as a pass-rusher, accumulating 33½ sacks, but he isn't limited to having great pass-rush skills.

"He can do it all," Cowboys coach Wade Phillips said. "He has tremendous speed and he's relentless."

Everything a team could want in a defensive end ... and an outside linebacker.