Disclaimer:  My previews of Big 10 teams are based on viewing of 2014 games of said teams plus extensive reading of local and national previews of that team.  I might be wrong in my assessment any one team or any specific unit of that team.  But that's clearly doubtful. (!!)  No, on a serious note I enjoy people who comment who live locally to these teams or is an opposing fan - helps us get a better perspective so if you are one feel free to add to the discussion. 

I also write this with the assumption Jake Rudock is the starting QB as the matrix of possibilities is too great trying to predict things with Shane Morris as a start.

TL;DR

After making what seemed like a "breakthrough" in 2012 with a 10 win season Northwestern began receiving the type of hype you are seeing with Minnesota this year as a top tier 2 team in the conference.  I've already outlined why I believe Minnesota hype will come back down to earth this year and it sure did for Northwestern.  Some of it was just bad injury luck but programs of this ilk rarely have the depth to go a whole season without a serious setback.   After back to back 5 win seasons Minnesota has basically replaced Northwestern as the chic program to pick as a challenger for the Nebraskas and Wisconsin in the West.   As for Northwestern, 2012 feels more like an outlier and if Northwestern doesn't get to 7 wins this year that will be 3 years in a row without a winning season.

Northwestern has ranked between 66th and 76th in the F/+ rankings in five of the last six seasons.

Vegas has set Northwestern's win line at 6.5 games and judging from their tough schedule this sounds fair.   Tough games with brainy schools Stanford (home) and a suddenly solid Duke (away) are mixed with FCS Eastern Illinois and quite bad Ball State.  2-2 seems likely.   (Duke is likewise breaking in a new QB but is well coached, and is at home)   Northwestern is probably sick of playing Michigan as UM has (at times undeservedly)  snatched some last second victories away but it doesnt get easier for the Wildcats in 2016-2017 as their crossovers switch from UM/PSU to OSU/MSU.    If they only go 2-2 in non conf they'd need to go 5-3 in the conf to go 7-5 and surpass Vegas 6.5 games.  That seems daunting with the schedule they have.  I might actually take the under on Northwestern this year.

The Wildcats should have a solid defense but at least in terms of preseason projections their offense lacks an established QB and a lot of threats in the receiving core; running back should be good and could be quite good if all goes well.  OL is questionable.  That said their defense should keep them in a lot of close games and its up to the offense to do something.

Last year

In many ways Northwestern was in a similar spot to Michigan entering 2014.  Coming off success a few years earlier but some stubbed toes in 2013, many thought Northwestern was a bit of a dark horse coming into 2014, and if things fell right could challenge in their division.  Two bad losses early killed that thought but by week 5 wins over Wisconsin and Penn State had restored the faith a bit and brought a 3-2 record.  It went downhill from there as Northwestern closed out the year 2-5, although their week to week performance was wickedly variant.   A team who in a span of 3 weeks could lose 48-7 to Iowa, then punish TV viewers with a 10-9 slog vs UM, and then beat a decent Notre Dame 43-40 in South Bend.  It was one strange year. 

Im terms of unit strengths/weaknesses - Northwestern had a horrid OL as measured by FootballOutsiders (83rd), which sunk down its FEI/S&P+ offense in the 80s to 100 range.  The defense was decent with FEI/S&P rankings in the 30s to 50s which was a bit behind UM.  At the total offense/defense unit level, Northwestern was a (barely) slightly worse version of Michigan.  But at least had a bevy of serious injuries and an almost lack of 4/5 stars anywhere in the program to blame it on.  

Northwestern was really boring to watch on offense last year:

Northwestern recorded only 34 plays of 20 yards or longer last season, fewer than all but three FBS teams.

Explosiveness is hard to quantify, but the IsoPPP (isolated points per play) stat does a pretty good job. In 2014, Northwestern's IsoPPP was .68, which was 128th in the nation.  (i.e. last in FBS)

At the individual level, QB Trevor Siemian was what you typically get with a Big 10 QB the past decade.  Nothing special - and often just bad.  While he threw for 2200 yards his yards per attempt were a pathetic 5.6 (for comparison in 2013 he threw for 7.2 ypa!).  And even with that short passing game his completion % couldn't bust 60%.  7 TDs, 11 INTs - it wasn't good.  Freshman running back Justin Jackson was a revelation later in the year and he piled up nearly 1200 yards with a 4.8 ypc average.  Michigan fans won't remember his name because UM's run defense stuffed him to the tune of 35 yards but aside from that game he had between 100ish and 150ish a game in all of Northwestern's final 8 games.  Considering the dour OL that was especially impressive.  

At WR - an ACL injury to Northwestern's top catching threat - led to relatively meh production from Kyle Prater (now in the NFL) and junior Dan Vitale.  Both had "2014 Darboh like" seasons; ok as complementary receivers but considering they were the top line guys it wasn't good.

Speaking of injuries, they forced some young players into key roles on the defense last year which didn't help 2014 but should help in 2015.

The 2014 defense was good at two things: preventing big plays on the ground (40th in Rushing IsoPPP+) and preventing completions through the air (43rd in Passing Success Rate+, 32nd in completion rate allowed).

Considering the lack of pash rush the 43rd ranked Passing Success Rate seems quite impressive.

Special teams were not great either as the Wildcats were 124th and 114th in punt and kickoff efficiency respectively.

This year

Northwestern returns 15 starters so that is (almost) always an asset.  However the bulk (10) are on defense so the offense will have major questions.  

Jackson returns for his sophomore year and should be the star of this offense if his last 2/3rds of his freshman year are any indication.  A year in S&C, a year to understand playbooks better and the ability for young RBs to really impact the game all contribute to this view.

The WRs were meh in 2014 but the return of Christian Jones - Northwestern's lead WR in 2012 and 2013 - from an ACL suffered last August should boost this group big time.

Like Minnesota, Northwestern should return a pretty darn good secondary.   3 of 4 starters return with Matthew Harris and Nick VanHoose a veteran duo at cornerback; Harris could be drafted.  Defense end is also very veteran while the DTs and OLBs are somewhat lacking. 

The schedule is not easy as along with Stanford and Duke the Wildcats have road trips to Michigan, Wisconsin and Nebraska while playing a neutral game at Soldier field vs Illinois.   The Wildcats host PSU, Iowa, Minnesota, and Purdue - none of these are gimmees (Purdue's offense could be good this year if Appleby is the real deal).   On the other hand Northwestern avoids the two top 10 teams in the conference in MSU and OSU.  I'd expect Northwestern to be playing a lot of games that hinge on the last drive.

As always, Bill Connelly's SB Nation preview is worth the read.

Here are a bunch of position by position analysis if you are that deep into Northwestern.

Northwestern Offense

Questions abound and until a QB is named (or a dual system) we won't really know what to expect. 

At QB senior Zack Oliver, sophomore Matt Alviti, and RS freshman Clayton Thorsons are in  competition.    Alviti is more of a (limited)  running QB while Thorson is more of the passer - he actually had an impressive recruiting profile out of HS - but still a newbie at the NCAA level.  Some speculation that Thorson is the leader.  While listed as a pro style out of HS the Wildcat previews have him more of a dual threat. Oliver had 57 attempts last year, completing just over 50% while throwing for 6.4 ypa.  Unless he improves on that production, Northwestern fans probably hope one of those younger guys beat him out.

The OL must improve (returns 3 starters) and if it does Justin Jackson could emerge as one of the best RBs in the league.  The WR corps should be boosted by the return of Jones. 

If you're going to lose three multi-year starters (combined: 101 career starts), you might as well lose them from a disappointing line. The Northwestern line was decent in two important categories -- stuff rate (avoiding run stops behind the line) and passing downs protection -- but didn't get a push in short-yardage situations. And it created fewer open-field opportunities for its runners than almost any line in the country.

Northwestern Defense

A mostly veteran group here with some young bucks ready to play due to being forced into action last year.  The defensive tackles seem to be an open area of concern however and the linebackers lost stalwart Chi Chi Ariguzo.

Ten of the 12 players with at least 2.5 tackles for loss return, as do four of the six with at least four passes defensed.

Matchups

(take these matchups with more of a grain of salt than usual because once you get past the month of September teams grow and evolve - well at least well coached teams.)

UM rush off v Northwestern rush def - Adv: Even.  Both teams have questions and until the season begins its too early to really determine who has what.  Hopefully by mid October UM has a viable rushing offense with lineman who create holes that running backs not named Drake Johnson can find.  Northwestern's questions at DT offer similar questions for their rush defense.

UM pass off v Northwestern pass def - Adv: Even.   This is only even due to Rudock.  Northwestern's back 4 should be quality - espt at corner -  but their pass rush might let them down.  UM's receivers are of course lacking in production as a whole and are more about potential until we play actual games.  Will it just be a group of complentary receivers complenting each other or will someone emerge by this time of the year?   Expect a lot of Jake Butt (again).

Northwestern rush off v UM rush def - Adv: UM.  This is only based on UM's performance last year and Northwestern's OL issues. Of the 2 teams Northwestern actually has the most proven back - which is sort of sad considering the multitude of high level prospects that filter through UM and the fact Minnesota's guy is a true sophomore.  Aside from the UM game, Northwestern was able to run on the remaining 7 of final 8 opponents but without a great OL I do expect UM to have the (slight) advantage.

Northwestern pass off v UM pass def - Adv: UM.   Northwestern needs to find an answer at QB.  Maybe they have one by week 6 - it is a great unknown.  Best case is Thorson grabs the jobs and begins to figure things out by this point in the year. The issue with UM is corner depth - this about the time of year your CBs begin to get dinged up and once you get past presumed starters Lyons and Lewis you begin to ask a lot of questions with the next group.  Healthy savvy CB starters would be a boon if that's the case. (safeties have more depth)  Northwestern doesn't have anyone who really scares you at WR but Jones should be solid.  Michigan's "weakness" has more potential answers than Northwestern's "weakness" at this point in time.

Overall

Like Oregon State I think the type of team Northwestern brings fits solidly into the type of team UM is built to stop.   Teams with good QBs scare me much more than those with "IDK", esp with UM's still "sorting it out" passing defense. 

The defense should have a solid day and if they can do anything similar to what they did vs freshman RB Jackson last year it should be a comfortable win.  While I'd expect Jackson to improve on his production and get nearer to 100 yards, rush defense should remain a UM strength especially up the gut.  So "future Northwestern QB(s)" will need to find a way to get some yards thru the air without a lot of potent weapons.

This is a home game, enough weeks into the season for the offense to (fingers crossed) have a viable rush offense and that shold parlay in Rudock being more effective as the offense can be more 2 dimensional.  Of course that is a lot of theories and we need to see them become fact by mid October. 

Northwestern will be coming off a smash mouth type of game vs Minnesota while UM will be returning home after a night game vs a (IMO) not too impressive Maryland squad.  However with MSU on the calendar a week after this game some Wolverines may be looking ahead. 

This is the type of game a Harbaugh led team - even in year 1 - should do well in.  Not to mention even Hoke's teams found magical ways to beat the unlucky Wildcats.