Mark Reynolds has powered Baltimore into an unlikely tie atop the division. (US Presswire)

Over the past weekend, Mark Reynolds produced a pair of two-homer games that pushed the Orioles to victories over the Yankees, helping the upstart Birds draw within striking distance of the Bronx Bombers in the AL East race. On Tuesday, with their deficit in the division race reduced to a single game, Reynolds continued his hot streak, bashing a three-run homer off the Blue Jays' Carlos Villanueva to key a 12-run onslaught. Backed seven shutout innings from Zach Britton and combined with the Yankees' second loss in as many days to the Rays, the O's now own a share of first place in the AL East, with the Rays just 1 1/2 games behind.

Just seven weeks ago, the Yankees owned a double-digit lead in the division and looked for all the world like a typical pinstriped juggernaut. On July 18, less than a week after the All-Star break, their record stood at 57-34, giving them a 10-game cushion over the 47-44 Orioles, with the 47-45 Rays another half-game back. Since then, the Yankees have sputtered, while the other two teams have soared:

Tm W L W Pct GB RS RA Pyth W Pct Orioles 29 15 .659 -- 207 170 .597 Rays 28 16 .636 1 188 104 .766 Yankees 19 25 .432 10 193 190 .508

Among AL teams, only the A's (29-14) have been better than the Orioles and Rays. Not coincidentally, Oakland and Baltimore entered Tuesday as the two teams holding the AL wild-card spots.

With less than a month remaining in the season, what are we to make of this race? In the grand scheme, the Orioles still look like the odd duck here, not only given their recent lack of success — they haven't posted a winning season, let alone reached the playoffs, since 1997 — but also their −19 run differential. By comparison, the Yankees are at +83, the Rays at +81. As I noted last month, only five teams have ever reached the postseason with a negative run differential: the 1984 Royals (-13), 1987 Twins (-20), 1997 Giants (-9), 2005 Padres (-44) and 2007 Diamondbacks (-20). When I wrote that, the Orioles were 57 runs in the red, but since then, they've cut that by two-thirds.

Concealed within that negative run differential is the Orioles' .774 winning percentage (on a 24-7 record) in one-run games, a record-setting pace; Saturday's 4-3 loss to the Yankees broke an astounding 13-game winning streak in one-run games. Couple that with an MLB-high .647 winning percentage (on a 22-12 record) in games decided by two runs, and Baltimore's .708 winning percentage in games decided by two or fewer runs is the third-highest of all-time . Meanwhile, even with Tuesday's win, the O's are still 21-22 in games decided by five or more runs, having been outscored by 23 runs in such games.

Baltimore's recent surge owes much to improved starting pitching. Since the beginning of August, the rotation's ERA is 3.90, and the starting five has delivered quality starts 63 percent of the time. Prior to that, they were at 4.09 — not too much higher — but delivering quality starts just 44 percent of the time. More than anything else, their consistency has improved. Of the five pitchers who have made at least four starts in that span, four of them — Britton, Wei-Yin Chen, Miguel Gonzalez and Chris Tillman — have delivered ERAs of 4.30 or lower; only Tommy Hunter (7.08 ERA) has been higher, and even that owes mainly to one three-inning, eight-run drubbing that bumped him back to Triple-A. It's worth noting that among that aforementioned quartet, only Chen began the year in the rotation; Britton was on the disabled list, while Gonzalez and Tillman were in the minors.

Even with that improvement, general manager Dan Duquette hasn't been content to stand pat. Last week, he acquired Joe Saunders from the Diamondbacks in trade, thus replacing Hunter; rocked by the White Sox in his first start, Saunders rebounded to throw 6 1/3 shutout innings against the Blue Jays. Later this week, the team is scheduled to get Jason Hammel back from the disabled list following an eight-week absence due to surgery to remove loose bodies in his right knee. With a 3.54 ERA and 8.7 strikeouts per nine, Hammel has been the team's most effective starter this year, and his return comes just as Tillman underwent an MRI that showed an inflamed ulnar nerve.

While the O's have gotten hot, the Yankees have cooled off drastically, in part due to injuries. When Alex Rodriguez went down with a fractured metacarpal on July 24, they were 58-39, still seven games up on the Orioles and eight ahead of the Rays. While the Yankees have gotten stellar performances from Derek Jeter (.335/.379/.525), Nick Swisher (.293/.377/.489) and third base fill-in Eric Chavez (.325/.387/.530) since then, Curtis Granderson (.192/.257/.400), Mark Teixeira (.232/.303/.389, and now sidelined by a calf strain), Raul Ibanez (.215/.311/.418) and Andruw Jones (.131/.239/.230) have all been dreadful, and newcomer Ichiro Suzuki (.274/.297/.403) hasn't helped much. Since winning seven out of eight games from August 8-15, the team has gone just 6-12 while failing to win back-to-back games even once. Since August 21, they have scored more than four runs just twice, and more than five runs just once. Rodriguez returned to the lineup on Monday, and while he's collected hits in both games, the Yankees have managed just five runs total. They haven't collected more than six hits in any of their last five games, their longest streak since 1990.

As for the Rays, they have now won four straight after a 1-6 slide threatened to derail their playoff hopes. They're 18-9 since the return of Evan Longoria, but the real story lately has been their pitching. Since yielding 10 runs on July 18, they have allowed a microscopic 2.36 runs per game. Their pitchers have limited opposing hitters to 0.4 homers per nine in that span while striking out 8.6 per nine and walking just 2.1. While the starters have been excellent (2.65 ERA), their bullpen has been positively lights out, delivering a 1.11 ERA while allowing just five homers in 121 1/3 innings. Four relievers have thrown at least 12 innings in that span with ERAs below 1.00, including Fernando Rodney, who has an 0.71 ERA for the entire season.