Those promotion odds don't necessarily mean Barnsley are favourites to beat Swansea. They just mean that if by chance Barnsley do manage to beat Swansea they stand a better chance against Brentford (or Bournemouth) than Swansea. Which would make sense. For me Brentford could well play Bournemouth off the park and subsequently thrash Swansea but of course Barnsley have shown they can disrupt them.