Signs is a good movie - what happened?

Signs was on tv last night and I caught it about half way through. I ended up watching the rest of it. You know when that happens, you start off browsing and then a movie hooks you in and keeps your interest? Well, that's what happened to me. The script is actually really funny, and the atmosphere is very tense. Mel Gibson and Joaquin Phoenix are perfect in their roles, hitting every mark with practised ease. The children, Rory Culkin and Abigail Breslin (much younger than her role in Little Miss Sunshine) are also perfect. It made me remember how once M Night Shyamalan was a good director/writer. Ok, so casting himself in the role of the vet who killed Mel Gibson's wife was a tad self indulgent, but nothing compared to his recent Lady in the Water, which was absolute drivel. Night burst onto the scene in 1999 with the Sixth Sense, which, until Lady in the Water, was my least favourite of his films. Everything is built up to the twist ending and, while it is well made and Brue Willis is good in it, I don't think it rewatches as well as his other films. Then came Unbreakable, a really good movie with an interesting concept that came along before everyone jumped on the superhero bandwagon. Next was Signs. It isn't a good example of an alien movie, but as a thriller and a look into how a family react to a global threat, without playing a big part, it is excellent. A lot of people didn't like The Village but, despite slight disappointment about one of the plot points, I thought it was a very good movie with really likable characters. Night's recent work, Lady in the Water, is so bad that it doesn't bear mentioning. Watching Signs again made me wonder - what happened? How come the promising career of a writer/directer good at creating tense atmospheres between a small group of characters just died in this messy puddle? Is there a lesson in hubris to be learned by us all through his example?