These aren't your father's left tackles

An era is coming to an end.

Maybe the beginning of the end was last year when Kansas City's Willie Roaf retired. This year, Jonathan Ogden is talking retirement after an 11-year career that might put his bust in the Hall of Fame. Though Baltimore coach Brian Billick and general manager Ozzie Newsome believe Ogden will play at least one more season, they won't know for sure until maybe after the draft.

But there's more. At some point, Walter Jones, who's 33, will retire in Seattle. Orlando Pace is entering his 11th season. Flozell Adams of the Cowboys and Tarik Glenn of the Colts are entering the final years of their contracts. Tra Thomas of the Eagles is 32.

Ogden, Pace, Jones, Adams, Glenn and Thomas were successes from 1996 and 1998 draft classes. It's been said a great left tackle can be a franchise cornerstone for a decade. Those six tackles answered the call. Now, as their careers wind down, who will be the tackles to replace them and will they be as good?

That's the question coaches and personnel directors are trying to answer and it's not that easy.

"Right now, pass-rushers are so good, you have to find a good left tackle," Newsome said. "If you can't find someone as talented as Ogden, you might have to fit your offense with some tight end help to stop some of the best pass-rushers. Otherwise, you get your quarterback killed."

Actually, the replacement process started two years ago. The difference is franchises have to be more open-minded and creative in the search for the left tackles of the future. Teams also have to accept that the left tackles of the future may not be as dominating as ones of the past.

Little did the Saints know when they drafted Jammal Brown as a right tackle in the first round of the 2005 draft that he would end up their left tackle. But coach Sean Payton and general manager Mickey Loomis made a risky decision a year ago. They traded aging left tackle Wayne Gandy to the Falcons and moved Brown to left tackle, a position they weren't sure would fit him. Brown ended up going to the Pro Bowl, quarterback Drew Brees had great protection all year and played like an MVP, Payton was coach of the year and Loomis was GM of the year.

Two second-rounders in 2005 also worked out as left tackles -- Michael Roos of the Titans and Khalif Barnes of the Jaguars. Their games are based more on athleticism than power. Last year, D'Brickashaw Ferguson settled into the Jets' left tackle spot minutes after the Jets made him the fourth pick in the draft. With Ferguson's help, the Jets made the playoffs.

This year's draft offers more hope of continuing the left tackle legacy. Joe Thomas of Wisconsin will be drafted in the top five and Levi Brown of Penn State won't be too far behind him. A rising first-rounder is Joe Staley of Central Michigan, who, like other left tackles, started his college career as a tight end and grew into a success story.

But don't try to compare the players of today to the guys they're replacing just yet.

Ogden is something of a freak. The 6-foot-8, 345-pounder moves like a basketball player boxing out a small forward. Pace came out of Ohio State with the reputation of being able to pancake defensive ends trying to get around him. Jones came to the Seahawks with unbelievable athletic ability. In high school, he pushed cars to gain strength and worked drills in a cage that allowed him to keep his body positioned low to stay in front of pass-rushers.

Many of the left tackles coming into the league now are a little lighter than those of the past. The knock last year on Ferguson was he might have been a little too light at 313 pounds. The 6-7, 311-pound Thomas has heard similar criticism. Teams want it all. They want left tackles with wide bases, but they also want them with the ability to move fast enough to keep up with 265-pound defensive ends.

"There may only be about six or seven left tackles who have the ability to play in space on every down and hold out a pass-rusher," Cardinals coach Ken Whisenhunt said. "That's an important part of your offense. If you have that type of left tackle and can leave him alone on a defender and not have to protect him by moving a tight end next to him, you have an extra receiver to put into your pass route. The good part of this draft is there are at least two guys like that."

Obviously, Whisenhunt was referring to Thomas and Brown. If the scouting reports on them are right, the offenses that draft them will have the luxury of not tailoring their schemes to provide extra protection. It's no secret the Seahawks and Rams had great success with their offenses because of Jones and Pace. Those left tackles were put on an island to block and their quarterbacks stayed upright long enough to complete passes.

The cost of a premier left tackle has become staggering. Ogden has been the highest-paid offensive lineman throughout the 2000s, making $8.3 million a year. Pace makes $7.557 million a year. Jones makes $7.5 million a year. And, with four guards getting contracts in the range of $7 million per year this offseason, the price of the left tackle position is only going up.

Which is why last year's draft was such a mystery. After Ferguson, who was taken fourth by the Jets, there were four potential first-round left tackle prospects, although some had knocks because of injury histories. Surprisingly, teams passed on them. Winston Justice of USC fell into the second round and went at No. 39 to Philadelphia. Marcus McNeill of Auburn dropped to the 50th pick and went to the Chargers in the second round. Charles Spencer of Pitt and Eric Winston of Miami fell to the third round, and the Houston Texans grabbed them both.

Talk about bargains. The Eagles believe Justice eventually could take over for Thomas. McNeill went to the Pro Bowl for the Chargers and they have him at second-round money. Spencer and Winston are still question marks, but the upside is there.

The sleeper in this year's draft is Staley, and his stock continues to rise. Staley still remembers the day during his sophomore year in college when a coach told him he was moving from tight end to tackle. At first, he was upset. One coach told him he might be a pro prospect if he made the conversion to tackle. So Staley ate six meals a day, power lifted and bulked up from 230 to 295 pounds.

"I think it's harder and harder to find the mauling type of left tackles, so teams are looking for blockers with athletic ability," Staley said. "I think it helps being athletic. I know teams are still finding it hard to believe I was a sprinter on my high school track team but I was."

The Falcons sent a sports nutritionist to visit Staley. It was determined he could add enough muscle to get to around 320 or 325 pounds. Staley may not grow into the dimensions of Ogden or Pace, but he's part of the next wave of left tackles.

John Clayton is a senior writer for ESPN.com.