A week-long survey of the preseason favorites for the BCS championship, and what they have to overcome to get there. Today: Alabama.

What we know. There is more continuity than the departure of eight NFL draft picks suggests: On offense, the Crimson Tide return their starting quarterback, A.J. McCarron, and four future pros on the offensive line who have combined for 97 career starts, opposite six returning starters from the most dominant college defense in decades. Seventeen projected starters are in their third, fourth or fifth year in the program. January's BCS Championship win over LSU was arguably the best game of McCarron's career, against a defense nearly as ferocious as his own.

At this point, though, expectations at Alabama aren't generated so much by anyone in the program, however experienced, but by the program itself. The pipeline of talent Nick Saban has constructed to Tuscaloosa over the last five years is beginning to resemble not just a factory but a monopoly. Since 2008, four of 'Bama's last five recruiting classes – the classes feeding the 2012 roster – have been ranked by at least one of the major recruiting sites as the best incoming crop in the nation, producing a perennial contender regardless of the annual attrition. Last year's national championship run came in spite of the loss of four first-rounders from the 2010 team (not to mention the starting quarterback, Greg McElroy), and once again, the new faces in the lineup this fall come with the full accoutrement of blue-chip accolades.

The most hyped of the lot, incoming tailback T.J. Yeldon, has already announced his presence as MVP of the spring game, and still he figures to split carries at best with juniors Eddie Lacy and Jalston Fowler in a crowded backfield. Not that it really matters with this offensive line who's carrying the ball at any given time.

What we don't. For the same reason, you can go ahead and mark down the defense as one of the best in the nation by almost any prevailing standard: Under Saban and Saban-bred coordinator Kirby Smart, the Crimson Tide have led the SEC in both yards and points allowed four years running. But the 2012 edition can only suffer in comparison to the bloodthirsty 2011 unit, which set a new cosmic standard by leading the nation in total defense, scoring defense, rushing defense, passing defense, pass efficiency defense and third-down defense, then bottling it in a paste made of LSU quarterback Jordan Jefferson in the BCS title game. Minus four multi-year starters who went in the first two rounds of the draft, a step back this fall may as well be written into natural law.

Even if it only goes down as a minor regression on the stat sheet, the difference could be critical in certain, specific situations when the offense is struggling, which is probably just as inevitable. In 2009, when the offense went into a temporary, midseason hibernation, the defense responded by holding opposing offenses to a grand total of three touchdowns over six games; the offense rebounded in November, 'Bama trounced Florida in the SEC title game to wrap up an undefeated season and went on to win the national crown without allowing more than 21 points in any game. In 2010, the defense was almost as good according to the final numbers, but broke just enough for the Tide to drop three games in which they allowed three touchdowns in a single half. Excluding a late-season scrimmage against Georgia Southern, last year's championship defense only allowed more than one touchdown in a game once, in a 38-14 win over Arkansas.

Over the course of a season, greatness is a question of consistency, and even then there are no guarantees – a heroic effort by the defense still couldn't stave off last year's regular season loss at the hands of LSU. But in lieu of a reliably explosive offense, a couple bad quarters by the new starting corners, Dee Milliner and Deion Belue, could be all it takes.

Where it can all go wrong. On that note, two of the first three games on the schedule are against seasoned senior quarterbacks, Michigan's Denard Robinson and Arkansas' Tyler Wilson, who will put the renovated defense through its paces in wildly varying fashions out of the gate; back-to-back trips to Missouri and Tennessee in October will present the same challenge against Mizzou's athletic James Franklin and the Volunteers' strong-armed Tyler Bray. Any of those dates are potential ambushes in the vein of South Carolina's out-of-nowhere upset over a very similar-looking Crimson Tide outfit in 2010, snapping the defending champs' 19-game winning streak.

But there's no point in trying to forecast a lightning strike. The preseason polls have already picked up where they left off last year, divided between Alabama and LSU at No. 1 and No. 2, and if all goes according to plan, the Nov. 3 rubber match in Baton Rouge will reprise the winner-take-all extravaganza of last year's 1 vs. 2 showdown in Tuscaloosa. (Albeit with one less week to build the hype, and a looming presidential election to ensure that it instantly dissipates.) In that case, of course, it was ultimately the loserof the regular season showdown that took the crown in January, though the extreme improbability of 'Bama's path to the championship game following that loss is probably the best argument against the likelihood of consecutive mulligans. No second chances this time.

Visions of champions past. Not to be too obvious, but when the head coach in question is less than nine months removed from his third BCS title, there's no need to go very far in search of precedent for his fourth. Like all of his teams, Saban's championship teams at Alabama in 2009 and 2011 and LSU in 2003 were all built on a conservative, run-first philosophy opposite arguably Saban's most malevolent defenses. (LSU in '03 and Alabama last year each led the nation in total yards and points allowed en route to the title; the '09 Tide finished second in both categories, behind only TCU.) There is not a dime's worth of difference between the starting quarterbacks on those teams, Matt Mauck, Greg McElroy and A.J. McCarron, all textbook examples of the unassuming, within-the-offense winner when not asked to do too much. On the other side, the recurring role of immovable nose tackle has been played by Chad Lavalais, Terrence Cody and now Jesse Williams. As the All-American, shutdown corner: Dee Milliner takes the baton from Corey Webster, Javier Arenas and Dré Kirkpatrick. The versatile, run-stuffing safety: First LaRon Landry, then Mark Barron, now Robert Lester.

One significant difference: The defenses on those three teams were all significantly more experienced at the start of the season than the Crimson Tide D will be in a few weeks. Meanwhile, the offense is making its annual preseason overture to "balance" under new coordinator Doug Nussmeier. But the not-so-secret Sabanball formula has never changed.

Crystal ball says…The most important part of any formula is recruiting the best players, which Saban has done more consistently than any other coach in America, and which leaves Alabama with no glaring weaknesses even in the wake of massive attrition to the NFL. The running backs are plug-and-play. To the extent it exists at all, the window for exploiting the new cornerbacks and outside linebackers is very small. If no one manages to take advantage of it during the first few games, the window may be shut by midseason.

From that point on, everything hinges on the slugfest with LSU. Get past the Tigers in one piece, and the only remaining hurdle is their ability to stay up long enough for the confirmation to come through on the tickets to Miami.
out of five.