How could this happen?

How could the Sox have lost so badly to the Jays? The Jays were a last place team in the AL East, and we lost two in a row. The first game I understand how we lost cause Roy Halladay is a great pitcher, but we had our ace up yesterday, and he gave up 15 runs! With Beckett that just doesn't happen, especially when he is up against a bad team. Also what's with the offense, there will be games where the Sox score tons of runs, and then the next day barely any!