Pocket hasn't always published twelve new novels a year. Just looking over this decade alone, there was no new novel scheduled for January 2010, March 2011, or January 2012. The difference is those months had reprints fill the MMPB slot, whereas this year we're just getting nothing on the gap months.
And once upon a time, there were two MMPB's out each month as well as more Trades and even Hardbacks. There is a real possibility that the line might be reduced further to allow better quality and allow them to be more of an "event"