The trouble for me is not any one particular issue in a vacuum but it's that it seems like the same issues have pretty consistently cropped up over MLF's tenure.
Some "week one rust" is to be expected, sure. But how many times now have we came out week 1 (or after the bye or extended breaks) and felt like we looked underprepared? It'd be one thing if this was the first time, but that's not the case.
Go back year by year. LaFleur's first season...we open with a 10-3 over the Bears. Later that season we come out after the bye and get smoked by SF, 37-8.
Year two we also open with a win - 43-34 over Minnesota, but nearly give it away...and again come out after the bye and this time get smoked by Tampa, 38-10.
Year three we get ran over by the Saints to kick off the season, 38-3. We win after the bye (45-30 over Chicago), but do also take a loss (to KC, admittedly) 13-7 after the "mini bye". We get a first-round bye in the playoffs, and return to lose to SF, 13-10 in the divisional.
Year four we again open the season with a loss, this time getting cooked by Minnesota. 23-7. We lose to Tennessee 27-17 on Nov 17, then have another "mini bye" and come out with extra prep to lose to Philly 40-33. (And then close the season with a 20-16 loss to Detroit in a game with everything to play for for us and nothing to play for for them)
Year five we open with a good win vs the Bears, but take a 19-17 loss to the Broncos out of the bye.
You get the picture. LaFleur does a lot of things well, but it seems like when an opponent is given a bit of extra prep time he's consistently the one caught flat-footed.
Go back through the game threads for the past few years and I suspect you will also start to note some trends in that - as above - it's just the same complaints over and over again. Questionable situational play calling. Bad clock management. Burning timeouts all over the place. Gets outcoached when opponent is given extra prep time. And so on. And that's not meant to be overly critical because every coach has blind spots and weaknesses, but if nothing else it's a bit bothersome that with LaFleur it seems like these same weaknesses have been known/visible for a while now yet there's little-to-no signs of improvement in these areas, either.
So, I don't know. Week One I guess I'd give it like a C, C-? Nothing too egregiously bad, but not exactly a coaching masterclass, either - just a pretty average day at the office with some suspect decisions that make me tend to grade maybe slightly below-average.