What do you mean SRH slipped of late? For 2012, their API score is 900. Here are all the HS in Poway:
Del Norte High 865
Mt. Carmel High 821
Poway High 868
Rancho Bernardo High 848
Westview High 872
So, in essence, SRH blew ALL of the Poway’s HS out of the water. 28 points higher than the highest PUSD’s HS (Westview). Even MMHS (861) would be ranked 4th in Poway School. 4 points away from Del Norte and 7 points away from Poway High and 11 points away from Westview. I’m sure API score does tell the whole story.
WRT OP, I think it really is school depending when it comes to special ed kids. Sometimes, it might even be teacher dependent. So, don’t assume that just because the whole district on average score high that they cater to special ed kids. Do you research on the actual school and even the teachers.