Due to security concerns raised as a result of the G-20 Summit in Toronto, MLB switches the Phillies’ scheduled visit to Canada to play the Blue Jays to Philadelphia. The visitors will be considered the home team, batting last, and can employ a designated hitter in the National League’s Citizens Bank Park.

Major League Baseball issues a warning to the Phillies after investigating allegations made by the Colorado Rockies that bullpen coach Mick Billmeyer used binoculars to steal signs from the centerfield bullpen in the game between the teams on May 10th. In today’s game, Colorado wins, 4 – 3, as Miguel Olivo goes 5 for 5, capping his perfect day with a walk-off home run off Chad Durbin in the 10th inning.

The Nationals continue to surprise, beating the Mets, 6 – 4, at Citi Field, thanks to Roger Bernadina’s first two homers this year. The second is a two-run shot off closer Francisco Rodriguez in the 9th inning and comes moments after Bernadina makes a diving game-saving catch to rob Jeff Francoeur with the bases loaded. Nats starter Craig Stammen contributes the other 3 RBI but does not figure in the decision; instead, reliever Tyler Clippard picks up his major-league leading 7th win, followed by Matt Capps’s 14th save, which is also a major league high so far this season.

Johnny Cueto comes within about a foot of a no-hitter when SS Paul Janish dives to stop Ronny Cedeno’s ground ball in the 3rd inning, only to see it deflect off his glove for a single. That’s the only base hit for the Pirates, as the Reds hurler records a 9 – 0 one-hitter. Chris Heisey gets his first three major league hits in the game, including a home run.

The Mariners’ key acquisition during the off-season, left-handed pitcher Cliff Lee, finally wins a game for his new team. After spending all of April on the disabled list with a strained abdominal muscle, and pitching well in his first two starts but being let down by an anemic offense, he pitches 7 1/3 strong innings in a 5 – 1 win over the Orioles. Brandon League then relieves Lee and finishes the game to earn his first save of the year, while Ryan Langerhans homers off loser David Hernandez, who is now 0-5.

In their first game since Dallas Braden’s perfect game, the A’s have to use 6 relievers to grind out a 7 – 6 win over the Rangers in 13 innings. Daric Barton drives in Landon Powell, who had just stolen his first major league base on a busted hit-and-run play, for the winning run. Barton had earlier homered in the 11th, only to see Texas come back against Tyson Ross for the third blown save by an A’s reliever on the night. Ross then strikes out when forced to bat in the 12th because of an empty Oakland bench, and later gets credit for his first major league win.

On the night they pay tribute to long-time broadcaster Ernie Harwell, who passed away last week, the Tigers beat New York, 5 – 4, with key contributions from three former Yankees. Johnny Damon, signed as a free agent in the off-season, hits a home run in his first game against his former team, while Austin Jackson drives in a run and Phil Coke gets two key outs late in the game. Jackson and Coke were both obtained in a trade for OF Curtis Granderson, who is on the disabled list.

The Nationals move to second place in the NL East with a 3 – 2 win over the Mets. Adam Kennedy and Ryan Zimmerman hit back-to-back homers in support of rookie Luis Atilano’s pitching. The Nats are now 4 games above .500 for the first time since September of 2005. After the game, the struggling Mets designate veteran Frank Catalanotto for assignment and call up OF Chris Carter from AAA Buffalo.

Dallas Braden pitches the 19th perfect game in major league history as the Oakland A’s defeat the Tampa Bay Rays, owners of the best record and best offense in the majors coming into the game, 4 – 0. Braden’s is the second perfect game in franchise history, following that of Catfish Hunter on May 8, 1968; it also comes less than ten months after Mark Buehrle pitched the last perfecto, also against the Rays, on July 23, 2009.

With their offense out of gas, the Mariners fire hitting coach Alan Cockrell and replace him with AAA hitting instructor Alonzo Powell. Seattle is hitting only .225 and has been outhomered as a team by Paul Konerko of the White Sox. The M’s respond to the change with an 8 – 1 win over the Angels as Michael Saunders hits his first major league homer and Josh Wilson also goes deep. Jason Vargas is the beneficiary of the offensive outburst.