EVANSTON, Ill. -- For the second time this season, Michigan football coach Brady Hoke called timeout with his team facing a 4th-and-short on its side of the 50-yard line.

Both times, he had sent out his punt team. Both times, the Wolverines retook the field with their offense. Both times, they converted.

It's a microcosm of why Michigan has been so good on offense this year: Its ability to consistently convert short-yardage plays, especially on third and fourth down.

No. 11 Michigan beat Northwestern 42-24 on Saturday to move to 6-0 and 2-0 in Big Ten play. In the game, it converted 14 of its 17 third-down attempts, including nine of 10 in the second half. It also converted its only fourth-down attempt.

The Wolverines are converting 58.1 percent of their third-down tries this season, which is third-best in the country. Against Northwestern, they were even better when needing 3 yards or fewer, picking up a first down or touchdown 72.7 percent of the time.

How has Michigan been so effective on these crucial, drive-sustaining plays?

It comes back, as it so often does, to quarterback Denard Robinson.

Michigan faced 11 third- or fourth-down situations needing 3 yards or fewer to achieve a first down or touchdown. Every time, offensive coordinator Al Borges elected to run the ball, with Robinson getting the bulk of those carries.

The junior quarterback got the call seven times, and picked up a first down or touchdown each time except once.

The Wolverines have one of the country's top rushing attacks -- it's currently ranked seventh -- which clearly is paying off in terms of sustaining drives and time of possession.

On the flip side, Michigan's defense is getting stops on these plays. After not allowing a third-down conversion against Minnesota last week, the Wolverines held Northwestern to 4-of-11 on third down and 0-of-2 on fourth down conversions this week.

Hoke has said most stats mean little to him, but one that does is getting third-down stops at about a 63- or 64-percent clip. His team is at 61 percent, but has been air-tight the past three weeks.

Against Northwestern, that kept the Wolverines' defense off the field and the ball out of the hands of the Wildcats' best player, quarterback Dan Persa. That was particularly true in the third quarter, when Northwestern had just two four-play drives.

The first ended with a three-and-out punt and the second with an interception by linebacker Brandin Hawthorne.

Michigan converted all four of its third downs in that quarter.

"I don’t know what time of possession was, to be honest with you, but I know in the third quarter our offense had the ball a while and the defense did a pretty good job getting the ball back," Hoke said.

The Wolverines held the ball for 12 minutes, 28 seconds of the third quarter and 37:57 overall. They're 28th nationally this year in time of possession after being 116th last season.

And, as several players have noted, this not only helps to score points, but prevent Michigan's defense from allowing them. Senior defensive tackle Ryan Van Bergen said last week his playing time has been reduced by as much as half in some games this year as compared to last year.

That bodes very well for Michigan as it prepares to face its toughest defense of the year in Michigan State. The Spartans feature the country's top overall defense, and they're No. 3 against the run.

So, it'll be the country's No. 7 rushing offense against the No. 3 rushing defense. Who wins?

'Two-quarterbacks' gets
mixed reviews
Michigan's two-quarterback formation, which puts backup quarterback Devin Gardner under center while Robinson remains on the field, was not as effective against Northwestern as it was against Minnesota.

Robinson lined up as a receiver this week after being in the backfield against Minnesota. This seems to be a less effective place for him, because it's unlikely Michigan would send him down field to catch passes -- and especially not over the middle. His options at wideout largely are limited to being used as a decoy or getting the ball on a reverse.

When Robinson is in the backfield, any number of plays could use him effectively, whether or not he touches the ball.

Still, the tweak in the formation serves the important purpose of giving Michigan State, the Wolverines' next opponent, a few more wrinkles for which to prepare. Robinson has been in the backfield and now at wideout, and Gardner has been a capable quarterback, whether he's throwing or running.

That's a strategic advantage for Michigan, considering the Spartans already have an extra week for game planning because they are coming off their bye week.

Countess' stock rising
Freshman cornerback Blake Countess turned 18 just two days before the start of fall camp. Now, he appears to be cracking the regular rotation on Michigan's revamped defense.

Senior cornerback Troy Woolfolk has started every game this year. However, it didn't take long for Countess to replace him on the field against Northwestern, playing alongside junior J.T. Floyd. The Michigan Radio Network reported the move was not because of injury. This means a few things.

• Either Woolfolk's various injuries are setting him back -- he's dealing with a sprained left ankle and broken right hand -- or Countess simply is pulling even with him in terms of performance. Or some combination of the two.

• Floyd is Michigan's undisputed top cornerback right now. This has become clear in recent weeks, as opposing quarterbacks have preferred to throw toward the corner opposite Floyd, but coaches seem to be embracing this as well.

• Countess has surpassed sophomore Courtney Avery as the third cornerback.

Countess has played remarkably well since getting his first defensive snaps against San Diego State. He allowed his first touchdown against Northwestern, getting beat on a fade to the corner of the end zone, but it still took a perfect throw to get it over him.

Coaches have been slightly reserved in their praise of Countess, despite his solid play. That could mean they are high on him and expect him to get more time in coming weeks, but don't want to build up expectations.

That would be the most logical explanation for why they would undersell what otherwise has been an impeccable debut.

Michigan goes big, goes low
Hoke said there were a couple specific defensive changes executed at halftime: He and defensive coordinator Greg Mattison elected to simplify their schemes, and they settled on a nickel sub-package as their primary personnel grouping.

"We went to a bigger group ... where a bigger-bodied guy could engage the receivers out there and maybe make something happen," Hoke said.

So, Michigan went with three linebackers and a true 4-3, instead of five defensive backs, which had not been working against the option that was shredding Michigan's defense. That put Jake Ryan, a big-bodied linebacker who plays on the strong side, on the field.

Sure enough, he blew up the first option of the second half, and Michigan didn't allow a point after halftime.

Michigan's in-game adjustments continue to pan out at an astounding rate. It's now outscoring opponents 114-21 in the second half.

Standing Pat
Northwestern coach Pat Fitzgerald, when asked about the personal foul he picked up after Persa was whistled down on a 4th-down play because his helmet had come off: "I have to worry about three kids' college funds, so I'll leave it at that."

Hello, Michael Shaw
Senior tailback Michael Shaw has slid up and down the Wolverines' depth chart more than anyone this year, going from the favorite to win the tailback job in fall camp to getting one combined carry in blowouts of Eastern Michigan and San Diego State.

Now, he's received eight carries against Minnesota and six against Northwestern. Important ones, too. He scored Michigan's first touchdown of the fourth quarter against the Wildcats, extending the Wolverines' lead from 28-24 to 35-24.

He received twice as many carries as junior Vincent Smith (three), who has complemented sophomore Fitz Toussaint as Michigan's primary ball carriers.

Why now?

It might be because of Shaw's speed. He's the quickest of Michigan's backs, and Northwestern was stopping runs up the middle. Toussaint, for instance, had 14 carries for only 30 yards.

Is Shaw here to stay? Likely not. Toussaint and Smith seem to be the Wolverines' best options. But, it appears the staff won't hesitate to go to him if matchups dictate it.

Player tweet
Senior tight end Kevin Koger, who uses the handle @KogerNotKroger, after the game:

"Nothing needs to be said lol"

Look ahead
The water cooler talk Monday morning: Can Michigan beat Michigan State for the first time in four years?

As was the case against Northwestern, and San Diego State before it, and Notre Dame before that, this will be Michigan's biggest test so far this year. It's in East Lansing. The Wolverines are playing well, but Michigan State has the country's top overall defense and an extra week to prepare because of an off week.

This is going to be a tough one to call, but if Robinson can limit his turnovers, Michigan should have a great shot at moving to 7-0 with its off week looming, then a home game against Purdue after that.

Michigan State's defense is so good, the Wolverines cannot afford to squander scoring opportunities. Conversely, the Spartans' offense has struggled so much, they may have a hard time scoring if Michigan doesn't give them a short field.

Turnovers will be a major key in this game -- as they so often are in rivalries.

Kyle Meinke covers Michigan football for AnnArbor.com. He can be reached at 734-623-2588, by email at kylemeinke@annarbor.com and followed on Twitter @kmeinke.