I'd be interested if this works, I've found flights into BOS are often a LOT more expensive than PVD or MHT, especially when flying in from the south.. examples:

One way CRP-IAH-BOS in Y $718
One way CRP-IAH-EWR-PVD in Y $359
One way CRP-IAH-EWR-MHT in Y $394

or

One way FLL-EWR-BOS in Y $743
One way FLL-EWR-PVD in Y $564
One way FLL-EWR-MHT in Y $574

Advance purchase round trips are similarly different (I picked a date a month+ out w/ sat stay and +-3 days)

RT SAT-IAH-BOS in X & I $416
RT SAT-EWR-PVD or MHT in L $208

Boston is a cash cow, I suspect because of no WN (MHT and PVD have WN). You'd think B6 would drive BOS down.. but not yet.