While the Orioles and Rays have made moves to trade away rental players for prospects in recent days, the Blue Jays have sat on the side, waiting for their turn.
Toronto appears ready to jump into the fray, according to a source, who said the Blue Jays appear close to finding a new home for left-handed starter J.A. Happ.
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The Yankees are "heavy in the mix," according to a second source, though no deal had been completed as of late Wednesday afternoon. The Brewers, who have lost Brent Suter to a torn ulnar collateral ligament, and Cubs are also believed to be talking to Toronto about Happ.
According to MLB.com's Adam McCalvy, Milwaukee outfielder Domingo Santana left his game at Triple-A after just two at-bats on Wednesday, though a source said it was just a double-switch. The Brewers did not appear close to making any trades as of late Wednesday afternoon. 
Happ, who is in the final year of a three-year, $36 million contract, is 10-6 with a 4.18 ERA this season, his first as an All-Star. Happ is 0-3 with a 7.41 ERA in four July starts, but a move to a contender could rejuvenate the 35-year-old.
From the Yankees' perspective, Happ's record against the American League East-leading Red Sox is particularly attractive. He has a 0.84 ERA in two starts against Boston this season, and he's 7-4 with a 2.98 ERA in 105 2/3 innings vs. the Sox lifetime. The Yankees and Red Sox will still play each other 10 times during the final two months of the regular season.
The Yankees have already bolstered their bullpen with the addition of lefty Zach Britton, who was acquired from the Orioles late Tuesday night for three prospects.
On Wednesday morning, the Red Sox countered with a deal of their own, sending lefty pitching prospect Jalen Beeks to Tampa Bay for right-hander Nathan Eovaldi. The Yankees, who had been scouting Eovaldi, are still looking to add to a rotation that looks thin beyond Luis Severino, Masahiro Tanaka and Carsten Sabathia.
Yankees general manager Brian Cashman listed Luis Cessa, Justus Sheffield, Jonathan Loaisiga and Chance Adams as internal options if his club isn't able to deal for a starter by next Tuesday's 4 p.m. ET non-waiver Trade Deadline.
"We're going to continue to evaluate," Cashman said on Wednesday during a conference call to discuss the Britton trade. "We'd certainly love to add to the rotation, but at the same time, we're evaluating the available players in the marketplace. … We have some alternatives with a strong 'pen. That's something that we're analyzing with the price tags that are being thrown our way on starting pitching options. It's good that we reinforced the 'pen, and it makes a strong fallback position for us."