Michigan defensive coordinator Greg Robinson looks at the scoreboard after his defense just gave up their second consecutive touchdown to Purdue during third quarter action of Saturday, November 7th's clash between the two teams at Michigan Stadium. After buiding a 30-17 lead, Michigan watched Purdue storm back and beat them 38-36 for the Boilermakers first win at Michigan Stadium since 1966. Lon Horwedel | AnnArbor.com

Woolfolk, who used the word "clueless" to break down aspects of Saturday's 38-36 loss to Purdue, had seen enough.

Not only on tape. But in a series of defensive breakdowns that has left Michigan's once promising season on the brink of disaster.

"I'm really frustrated because we're too far into the season to be making those mistakes," Woolfolk said on Monday.

With Michigan's bowl hopes dwindling with stiff tests remaining against Wisconsin and Ohio State, the Wolverines mistake-prone defensive backfield continues to falter.

Against the Boilermakers, Michigan gave up 367 yards through the air, including a 54-yard Joey Elliott touchdown pass to a wide open Cortez Smith that gave Purdue a 31-30 lead. On occasion, defenders lost sight of their man in Michigan's man coverage which opened the door to big plays as the Boilermakers erased what was once a two-touchdown deficit.

"I don't know what's going on," Woolfolk said after the loss. "Everybody's just clueless."

On Monday, Woolfolk said his assessment didn't extend to the whole defense, but to individual players. When told of his cornerback's characterization, Rodriguez sighed and replied, "That's disheartening."

And although it may be easy to blame inexperience in the defensive backfield or a new defensive scheme under first-year coordinator Greg Robinson, Michigan seemingly finds new ways to put itself in bad situations.

"It's not the same guy all the time," Rodriguez said on Monday. "Those are things that are hurting us defensively and we're not good enough to overcome those. That's obvious. We cannot have those big mental errors or those big misses like that and expect to stop anybody."

After 10 games, Michigan is ranked last in the Big Ten in total defense (440 yards per game), last in rushing defense (191 yards per game), last in pass efficiency defense and last in scoring defense (33.3 points per game).

Despite the defensive struggles, Woolfolk believes he and his teammates are more comfortable in Robinson's system than they were last season under defensive coordinator Scott Shafer. And although he sees the secondary preparing well during the week, he's grown tired of the breakdowns that occur on Saturday.

Despite the lapses, he's not willing to blame a lack of familiarity with the scheme for the secondary's troubles.

"I don't think you can use the excuse anymore that (the system) is something new because we've been doing it for the whole season," Woolfolk said. "It's just a matter of being able to finally get it down and execute to perfection.

"It's the little things that's causing us to lose games."

And with only two games left to become bowl eligible, the little things are adding up to big frustration. After Saturday's loss - Michigan's fifth straight Big Ten setback - junior cornerback Donovan Warren acknowledged that a lack of execution on the part of a few was taking its toll on the Wolverines' overall defensive execution.

"It's different mistakes just on certain plays and we've got to do a better job," Warren said. "There's a lot of mental mistakes that are going on and it may be only one or two (errors) in the game and that may not seem like a lot, but those one or two can be a touchdown and can be the difference between winning and losing."

Jeff Arnold covers sports for AnnArbor.com. He can be reached at jeffarnold@annarbor.com or 734-623-2554.