Jose Reyes and the Jays are atop the AL East thanks to an eight-game win streak. (Tom Szczerbowski/Getty Images)

The Toronto Blue Jays have won eight straight games and 11 of their last 12, and at 19-7 (.731) have baseball's best record this month. As a result, they have opened up a three-game lead over the second-place Yankees in the American League East and have the fourth-best record in the majors this season as they chase their first postseason berth since winning the second of back-to-back World Series titles in 1993.

Had Toronto done this a year ago, after an offseason in which it added shortstop Jose Reyes, leftfielder Melky Cabrera and starting pitchers Mark Buehrle, Josh Johnson, and R.A. Dickey, the last the previous season's National League Cy Young award winner, it wouldn't have come as a surprise. Instead, the Jays won just 74 games in 2013, just one more than the year before they added those five former All-Stars to their roster. This year, with Johnson having moved on and catcher Dioner Navarro having been its only significant addition over the winter, Toronto's sudden surge to the top of the standings seems more suspect.

The engine behind the Blue Jays' success isn't hard to detect: They are tearing the cover off the ball. The 143 runs they have scored in May are 17 percent more than the next most productive teams in the majors (Detroit and, surprisingly, Cleveland) and work out to 5.5 runs per game. They've hit .275/.341/.497 this month as a team, leading the majors in May OPS by nearly 50 points with a .838 mark and in OPS+ by 13 points at 133. On the season, they trail only the Rockies and A's in runs scored per game and are first in the majors in OPS+ at 115, just edging out the A's, who despite the favorable ballpark adjustments, simply don't hit for enough power relative to Toronto.

Power is indeed the key element in the Blue Jays' game. They lead the majors with 76 home runs (nine more than the second-place Rockies). Edwin Encarnacion is second in the majors with 16 round-trippers, 14 of which have come in May, tying Jose Bautista's franchise record for most home runs in a single month. Bautista himself has 12 for the season. Including those two, six Blue Jays have hit eight or more home runs on the year (a 25-plus-homer pace). Included in that group are Brett Lawrie, whose previous season high is 11; Cabrera, who hit just three last year and whose previous high is 18; and early-April addition Juan Francisco, a lefthanded hitter whose previous high is also 18 and whose hot hitting has earned him starts at third base against righthanders, pushing Lawrie to second base in those games.

As those histories suggest, Toronto's offense is playing over its head. There are reasons to be cautiously optimistic about the power surges of Lawrie, who slugged .489 in the minors and .580 in 171 plate appearances as a rookie, and Cabrera, whose poor 2013 can be blamed on a benign tumor on his spine which caused back and leg pain and weakness. However, Lawrie is a lock to spend some time on the disabled list every year, and Francisco, while his power has never been in doubt, is likely to regress with increased exposure (he has just 114 plate appearances on the season).

There are three other Blue Jays hitters enjoying small-sample success that is unlikely to last. Adam Lind, who missed three weeks with a back injury, is hitting .341/.419/.573 in 93 PA while splitting time between first base and designated hitter, and, justifiably, avoiding lefthanded pitching like the plague. R.A. Dickey's personal catcher, Josh Thole, is hitting .360/.429/.400 in 56 plate appearances, and utilityman Steve Tolleson is hitting .311/.392/.622 in 51 PA having ascended into the short side of the platoon with Francisco, starting at second base against lefties with Lawrie returning to third in those games.

Francisco, Lind, Thole and Tolleson will all regress, Encarnacion is sure to cool off at least a little, and if any of the often-injured quartet of Lawrie, Reyes, Cabrera and Bautista experience further health problems it could undermine the lineup's early success.

Still, the offense should remain productive. Encarnacion, though unlikely to hit 14 homers in 21 games again this season, has established a new level of performance over a long enough period for his start this season to be accepted as real. The same can now be said about Cabrera, who has returned to his 2011 and '12 level this season after being derailed first by a performance-enhancing drug suspension and then that spinal tumor. Reyes is a four-time All-Star. Lawrie is a former top prospect and still just 24, so a breakout remains well within the realm of possibility (though outside of those eight home runs, he has not hit much this season). Lind at least has value against righthanded pitchers, and Thole and Tolleson have proven on-base skills. The offense is thus well-constructed, though a mid-season move to fortify second base may yet be required.

The pitching staff is a bigger concern. The Blue Jays issue walks more often than every other team in baseball except the White Sox, and their rotation leads the majors in free passes despite being 16th in innings pitched. Overall, the rotation has been average at preventing runs, but even with closer Casey Janssen having yet to allow a run after debuting on May 12, Toronto has the the second-worst bullpen ERA in the majors, a 4.96 mark that is lower than only that of the Astros' relievers. The 'pen's woes have been exacerbated by the regression of 2013 All-Star relievers Brett Cecil and Steve Delabar, the latter of whom has seen his strikeout rate fall precipitously this season.

The staff's bright spot has been Buehrle, the man with the iron arm, who leads the majors with nine wins (against only one loss) and has a 2.33 ERA and an AL-best 179 ERA+ in his first 11 starts. A shift away from his cutter in favor of his curveball appears to be playing a role in his success, though his lack of home runs allowed (just two in 73 1/3 innings) seems like a product of luck more than skill. Another potential warning sign: Buehrle's other peripherals are no better than they were a year ago, when his results (12-10, 4.15 ERA) were merely average.

Elsewhere in the rotation, prospect Drew Hutchison's reemergence in the wake of August 2012 Tommy John surgery has been encouraging, but Hutchison is not yet, and may never be, a front-of-the-rotation arm. Dickey continues to regress from his Cy Young height, thus far struggling to show the control that had distinguished his knuckleballing abilities in New York. The back of the rotation, meanwhile, remains a question mark with Dustin McGowan recently banished to the bullpen and Brandon Morrow once again on the disabled list, this time with a finger injury that could keep him out until the All-Star break. Not helping the pitching staff is the fact that Toronto remains a poor fielding team.