"Andy's Play" has everything needed for a classic "Office" episode: romantic misunderstandings, awkward moments, and, of course, plenty of Michael being Michael. But while it was good television--I laughed frequently--it just didn't have the same transcendent feeling as great episodes of the show. I count three reasons.
First, it just wasn't quite as funny. Now, humor is a notoriously subjective thing, but I think it's clearly the case that there weren't any big set pieces in this episode. (Think Michael wearing a sumo suit to work, or the bat loose in the office.) The show has struggled to find those big moments as it runs out of possibilities for its characters. In fact, the last great episodes of the show were in Season 5, when Michael formed his own paper company and somehow outwitted Dunder Mifflin. You can't exactly do that every season.
It could also be the case that we're so familiar with the humor of "The Office" that it just doesn't have the same impact on us. I would guess the problem is some combination of the two.
The second issue: the romantic entanglements. This episode dredges up the old Dwight-Angela connection, which stretches back to Season 2. The other pseudo-romance was between Andy and Erin, another leftover (this one from Season 6).
These relationships have the same problem as almost all "will they or won't they" storylines on television: 95 percent of the time, they will. The only reason for the romantic tension is to allow writers to drag out a storyline over dozens of episodes.
But there's a deeper problem as well. All of these characters--Dwight, Angela, Andy, and Erin-- are primarily here for comic relief. They're almost caricatures, far more one-dimensional than the main characters: Jim, Pam, and Michael. This is why we rooted so hard for Jim and Pam. It's why we even rooted for Michael with Holly. The man is a jerk, but we know why he's a jerk: a painful, fatherless childhood. (Whereas Dwight is just kind of a jack ass.) Unfortunately, the show can't keep these three characters in romantic limbo year after year, so instead it has to invent new couplings.
The final problem was Steve Carell. The man is responsible for an absolutely classic comic creation in Michael Scott. But here he just seems to be on auto-pilot. A bit in which Carell acts out an entire "Law and Order" episode for an audition should be hilarious, but instead it's merely funny. Likewise, Carell looks half asleep in the big opening montage for Season 7.
It's not hard to see why Carell moved on. He was sick of portraying the same selfish nincompoop season after season. That's understandable--although his film career, which mostly consists of paydays like "Evan Almighty" and dreck like "Dan in Real Life," doesn't seem any more rewarding.
Pop culture snobs will say that "The Office" should have followed the model of its British counterpart: two seasons, a special, then over and out. But "The Office," like many shows, was struggling to find its voice during its first season. Few can be brilliant right out of the box, as Ricky Gervais' "Office" was. I can't say exactly when the right time would have been for the American "Office" to call it quits. But it certainly seems past its sell-by date now.