Right. But since the fairly alarming decline from the dizzy heights of the Invincibles in 2004 to 2006 when we got (I think) our lowest points total under Wenger there has been a fairly consistent level.
Consistently not good enough, but the last 10 years have NOT been ones of steady decline.
Whether last season's 5th place was the start of another drop in level remains to be seen. It's certainly possible, if we lose Ozil and Sanchez without replacement then even probably. But it's impossible to know right now.