Coaching changes:

There is not a team in the NFL that made a more drastic shift in offensive philosophy than the Detroit Lions.  The Lions threw the ball more frequently than any other team in the NFL (66% pass plays).  They attempted the fewest rushes, and as a result had the second worst time of possession in the NFL.  Rod Marinelli got sick of the Mike Martz high-risk/high-reward offense leaving his defense on the field all game, so he decided to make a change.  Offensive line coach Jim Colletto has replaced him and been given marching orders to implement a run-oriented, ball-control offense.

O-Line:

The Lions drafted Gosder Cherilus to start at Right Tackle replacing George Foster and Damien Woody.   Foster gave up 9.5 sacks and led the NFL in false starts until he was replaced by Woody who wasn't much better.  The rest of the sub-par O-line returns.  It is hard to assess how much of the 54 sacks (3rd most) and worst rushing attack in the NFL is the fault of the players, and how much is the fault of the play-calling.  They ran the ball at 4.0 yards/carry, which is exactly average in the NFL, so it's not like they can't run block.  They were just never given an opportunity.  Still the group is suspect until proven otherwise, but likely improved.

QB:

Attention every man woman and child on the Jon Kitna bandwagon: bail out!  Kitna has been useful as a fantasy QB the last 2 seasons ONLY because of the volume of passes thrown.  His efficiency is nothing special, and with the new offense, his numbers will plunge.  No more 4,000 yard seasons.  3,200 may be the limit, with around 15 TD's and 15 Int's.  That is assuming he doesn't get yanked for Drew Stanton.  Kitna is 36, and is not the future of the franchise.  A change is coming eventually.

RB:

I actually really like whoever gets the bulk of the carries here.  Everyone who does not pay very close attention will be avoiding Lions running backs like the plague, so if anyone claims the job coming out of camp they are a big time sleeper.  My money is on rookie Kevin Smith to win out over Tatum Bell.  Bell has one 1,000 yard season running behind a Broncos O-line but has done jack crap every other year.  Smith was a workhorse in college and fits what the Lions want to do on offense.  Brian Calhoun is a wild-card, but I don't expect to hear much from him.

WR:

Mike Martz is gone and that means it's the end for all third receivers.  Mike Furrey and Shaun McDonald's careers as useful fantasy receivers are over.  Roy Williams and Calvin Johnson won't see a big decline in passes, it's everyone else who will suffer.  The Lions have signed every run-blocking TE available.  They will use 2 TE and 2 receiver sets.

Roy Williams should be drafted as a bottom end WR2.  He has a lot of talent but can't seem to stay on the field.  In his 4 seasons, only once has he topped 1,000 yards.  His career high is 8 TD's.  He was on pace for a good season in 2007 but missed the last 4 weeks and finished with 836 yards, and  5 TD's.

Calvin Johnson will overtake Williams as the top receiver very soon, possibly this year.  2007 was a little disappointing for fantasy owners, but that was impacted by a back injury Johnson suffered in week 3.  The remainder of the season Johnson was taking vicodin twice a game to play through the pain.  A healthy Calvin Johnson is capable of a large bump from his 48 receptions, 756 yards and 4 TD's even with the change in offense.  I am very seriously considering drafting Calvin before Roy.

TE:

Let's see, the Lions have on their roster: Dan Campbell, Sean McHugh, Casey Fitzsimmons, John Owens, and then acquired Michael Gaines.  What do these guys all have In common?  None of them can catch, all of them are blockers.  Don't draft any of them.

Defense:

What a strange brew this group cooked up last season.

Worst yards per game allowed.
Second most fumbles caused and recovered.
2nd worst in the league on third down.
Top 10 in sacks.

Rarely does a defense that makes that many big plays find itself as the worst in the league.

Free Safety Kenoy Kennedy was replaced by Dwight Smith.  This is a very slight upgrade as both players have been on the decline.   The Lions traded away Shaun Rogers and signed yet another ex-Tampa Bay Buccaneer to replace him in Chuck Darby.  This is a slight downgrade.  Rogers has more talent, but was on the sidelines sucking oxygen as often as he was on the field. 

The Lions substantially upgraded their secondary.  CB Leigh Bodden, who was acquired in the Shaun Rogers trade, is a vastly underrated corner.  He recorded the 6th most passes defended (21) and 5th most Interceptions (6) among defensive backs and recorded 88 tackles.  Brian Kelly was signed from Tampa Bay after he had lost his starting job there.  Still, both are large upgrades over Travis Fisher (who is now a backup) and Fernando Bryant (who signed with New England).

The Front 7 is thin, which means opposing teams will be running early and often.  Combine that with the Lions own plan to run, and you should see some much lower scoring games.  The Lions aren't worth drafting, but may be worth picking up for some spot duty (they play Atlanta, San Francisco, and Chicago, in their first 4 games).