No Holds Barred.
The Lions finally make it into the NFL playoffs for the first time since 1999. You remember 1999 right? Y2K, 56k Modems, and the Lions holding practice in Saginaw (sans Barry Sanders). Well, in keeping with the 90's the Lions saw fit to lose in the first round of the playoffs with a score of 28-45 after leading the game at half time.
So what happened? Simple really, the strength of the Lions D, and in fact the entire base principle of the defense, is a strong pass rush from the 4 on the D-Line, and that was totally negated, not by anything other then the refs allowing the players to play. In other words, they never called holding on the Saints, not once, despite repeated holds. Now it's true a hold could probably be called on every play, and it's also true that the Lions didn't get called as often as they held, but the Saints OLine took it to a new level and completely neutralized the Lions strength of their defense by holding all game long, blatantly, and with no repercussions.
That left it a shoot out, and a shoot out it was. The Lions are in the playoffs with a rookie WR, a 23 year old QB, and a ton of pressure. Still, until the mistakes started piling up in the 3rd and 4th quarter things were going rather well (for the offense). Stafford ended up 28 of 43 for 380 yards 3 TDs (and 1 Rushing TD) but with 2 INTs. Compare that to Brees' 33 for 43 for 466 yards and 3 TD's with no INTs. Calvin Johnson had 12 catches for 211 yards and 2 TDs, however, the entire Lions team managed only 32 yards rushing, that's not going to win you many games in the playoffs.
The Lions will need to address the run game somehow this off season, be it OLine, RBs, scheme, whatever. They will also need to work on the D some more (but we already knew that). There's a lot of work to do this off season with free agents (not so much getting free agents but not losing free agents) and then there's the draft where the Lions will be drafting somewhere in the early 20's. I've heard calls for replacing the DC but I don't think it's the scheme so much as continuing to build the talent on defense.
The Lions need to be able to play no holds barred football, and they need to do it against referees who bar no holds.