While LSU may be even better on defense next year, they will only maringally be better. In other words, they only have so much room for improvement. I contend that part of the difference between 3-star and 4 and 5 star recruits is that more 4 and especially 5-star recruits come in ready to play earlier. I think that a lot of the players that Dooley has brought in so far will probably need more time to develop, but may be able to end up being top players. The other issue is that LSU will likely have more players leave early because they have more that can.
It is too early to expect Dooley to compete wit LSU and bama.
We competed against L$U for an entire game, minus three seconds last year, on the road. We only made it to half time this year.
Last year we got blown out by uga, this year we stayed with them, for a half.
Last year bamer pulled away for a win. I do not expect it to be as "close" this year
To answer your question, yes it is realistic to expect the VOLS to compete with any SEC team.