What's wrong with college football championship contenders?

Nobody’s perfect — not even Alabama.

Each of the main preseason contenders for the College Football Playoff has indicated some flaw or flaws through three weeks, with several teams in need of immediate improvement to remain part of the national championship conversation.

That may even be true of the Crimson Tide, who have two wins against Power Five competition despite issues developing a consistent running game.

But the Tide are in great shape compared to Clemson and Ohio State, which have struggled on offense and defense in posting early-season losses. From Alabama on down, these are the problems that have stymied the best teams in college football.

Alabama: running game

The lack of production on the ground is an unforeseen development for an offense that has ranked lower than fifth in the SEC in yards per carry just once since claiming the first of six national championships under Nick Saban in 2009. A year ago, for example, Alabama ran for 189.8 yards per game and scored 35 rushing touchdowns against SEC competition, bullying opponents up front and freeing up historic seasons from wide receiver DeVonta Smith and quarterback Mac Jones.

Jones' replacement, Bryce Young, has met expectations and been a calming presence despite his youth and inexperience. The first-year starter is the only Football Bowl Subdivision quarterback with 10 or more touchdown passes without an interception.

But the running game ranks 95th in the FBS in yards per game (132.0) and 81st in yards per carry (3.9) and touchdowns (four). Those numbers are even worse if you remove Football Championship Subdivision opponent Mercer from the equation, which drops the Tide to just 3.6 yards per carry.

While able to beat Florida on the road, Alabama was held under 100 yards rushing for only the second time in its last 97 games. In 31 meetings against ranked opponents between 2015-20, the Tide averaged 183.1 rushing yards per game and 4.7 yards per carry with 57 touchdowns.

Georgia: health on offense

You need to look close to find anything noticeably wrong with the Bulldogs, who have Power Five wins against Clemson (10-3) and South Carolina (40-13) to go with a romp against Alabama-Birmingham (56-7). That easy win against the Blazers came without JT Daniels, who missed the game due to an oblique injury. In his place, Georgia drew 301 yards and five touchdowns on just 12 attempts from backup Stetson Bennett, who opened last year as the starter before being replaced late in the regular season.

Daniels' injury is a concern for an offense that has hit a higher level of explosiveness with him under center, the win against UAB notwithstanding. But he's not the only skill player dealing with injuries: Georgia also has been down tight end Darnell Washington and wide receivers Arian Smith, Kearis Jackson and George Pickens.

Getting Daniels back at full strength and providing him a full complement of receivers would help the Bulldogs avoid relying primarily on an outstanding defense to get past opponents such as Arkansas, Auburn and Florida.

Oklahoma: quarterback play

Spencer Rattler had five touchdowns and no interceptions in Oklahoma's 76-0 rout of Western Carolina but has been pedestrian in the Sooners' sloppy, borderline troubling wins as heavy favorites against Tulane and Nebraska. In those two games against the FBS, Rattler is averaging 7.1 yards per throw — a full two yards below his average against FBS teams a year ago — with just two touchdowns and two interceptions, erasing the early-season hype around his push for the Heisman Trophy.

Some blame can be attributed to an offensive line that hasn't bulldozed opponents and reliably opened up lanes for Kennedy Brooks and Tennessee transfer Eric Gray, which has allowed defenses to exploit Rattler's eagerness to make the splash throw instead of opting for safe plays that can extend drives, frustrate defenses and open up the full swath of coach Lincoln Riley's playbook. Sometimes for better but not infrequently for worse, confidence has never been an issue for Rattler.

Clemson: offensive line

The Tigers have scored 17 points in eight quarters against Power Five opponents Georgia and Georgia Tech. Some numbers are even uglier: Clemson is averaging an ACC-worst 3.7 yards per play, with an abysmal 2.5 yards per carry and just 5.6 yards per throw; has given up seven sacks, more than all but a dozen Power Five teams; has turned the ball over five times after doing so 15 times all of last season; and has just one gain of 40 or more yards.

If anything, the Tigers' offense has looked even worse than the numbers suggest.

The plummeting production can be tied to depth and chemistry issues with an offensive front that returned minimal experience and has looked unprepared for the regular season — first in coming up well short of the physical challenge posed by Georgia and then by not being cohesive enough to adapt to the Yellow Jackets' defensive game plan.

That's resulted in a disappointing start for quarterback DJ Uiagalelei, who has thrown for 475 yards in three games after going for 439 in last year's memorable loss to Notre Dame alone. If not fixed, the Tigers may not be able to win the ACC, let alone notch a seventh straight appearance in the playoff.

Ohio State: defense

There's been some predictable scrutiny of quarterback C.J. Stroud, who has stepped into the void left by Justin Fields and alternated moments of effectiveness — in the second half against Minnesota, for example — with extended periods of misfires and wobbly decision-making. While he'll miss this Saturday's game against Akron with a shoulder injury, Stroud still represents the Buckeyes' best option at the position.

It's the defense that's failed OSU through three games, in a stretch of putrid regular-season play nearly without precedent since Urban Meyer rejuvenated the program in 2012. Only twice during that span, in 2018 and in 2012, have the Buckeyes allowed at least six yards per play in back-to-back games, as they did against Oregon and Tulsa. In the regular season or otherwise, this stretch marks the only time since 2012 that OSU has allowed 500 or more yards in two straight games.

Since Meyer's arrival, the only non-pandemic year with similar defensive struggles was 2018, when the Buckeyes ranked 71st nationally in yards allowed per game and 72nd in yards given up per play. The next year, the OSU defense led the FBS in both categories.

So far, blame has fallen on coordinator and longtime assistant Kerry Coombs, who did not call plays in the win against the Golden Hurricane. In his place, coach Ryan Day handed those duties to secondary coach Matt Barnes, an arrangement that is expected to continue against Akron and into the heart of Big Ten play.

Coombs has played a vital part in the program's success as the defensive backs coach and should remain a key piece of the puzzle moving forward. But that rebound in 2019 was driven by offseason coaching changes, including the inspired decision to hire current Boston College head coach Jeff Hafley as co-coordinator.

If it'll take similar moves to lift this defense, is it possible to salvage a more respectable performance out of the wreckage of these first three games, or are the Buckeyes destined for a frustrating 2021 season?

Follow colleges reporter Paul Myerberg on Twitter @PaulMyerberg

This article originally appeared on USA TODAY: College football title contenders have flaws. What they need to fix.