FanGraphs introduced a new statistic a month ago called Expected Run Differentials (xRDiff), where they use their various metrics and weights to estimate how many runs a team should have actually scored and allowed, as to how many they really did. Here is the chart from last month. As you can see, the Blue Jays ranked 17th in the majors, and 8th in the American League at the conclusion of April.
Yesterday they released the numbers for the month of May. Over the last month, the Blue Jays have played better than they should have, which has given them a run difference of +30 (14 more than their expected total). Despite this fact, the Jays have still improved enough to bump their rank by 6 places and finish the month in 3rd place among AL teams (9th overall), behind only the A's and the Angels.
What we can take from this is that the NL teams seem to be doing a whole lot better as a league, the AL East is a shell of its former self (at least, thus far), and the Jays have shown some very welcome and long-awaited improvement in all facets of the game. It is also worth noting that, had FanGraphs published this on June 1st, as opposed to May 30th, like they should have, there would be another 10 runs in there for the Jays somewhere, thanks to today's blowout.