Partly, they're reaping the effects of getting rid of Mick McCarthy. Not saying he's a brilliant manager, but he's solid enough and in his six years there, they never finished lower than 16th. Showed him the door because they believed someone else could have them pushing more strongly towards the playoffs, and it's bitten them in the behind in the worst way.
But anyone thinking that they'll be anything other than a major threat in League One next year is deluding themselves. The financial gap between Championship and League One nowadays is massive - their wage bill last year was at least three times the size of ours. They don't have financial issues, because they've got an owner who's seemingly willing to cover large losses every season. I'll be shocked if they don't end up at least in the top six (like Barnsley & Sunderland this year, and Wigan, Blackburn & Rotherham the year before).
The only reason that next year's league might be a little easier is because Bolton are a complete financial basket case and they may have to trim their costs so much that they aren't at a massive competitive advantage over the likes of us...….