Not sure where the NEFL sits TBH.
BSR played Mallala in a trial game earlier this year and I believe won in a fairly close one...who knows who had playing not playing etc.
At a guess I would say a BSR would be competitive in the BL&G but the NEFL does fall away a fair bit especially the bottom A grade sides and then the B Grade comp where most teams are using at least 2-3 never played or over 45 year olds on a weekly basis.