It is very confusing, mostly because TPTB made it so and evaded the labelling with a lot of the characters but in the case of Matt and Julie they actually made it canon.

They SO implied that Lyla was a senior first season along with Jason. And now she's still in school? I could have seen how Riggins might have been behind, or Tyra, but Lyla? Ahahahahah. Yeah, right.