Peralta didn't have much of an explanation for the pine tar, of which umpiring crew chief Tim Tschida said there was "a significant amount" in the glove.
"That's my BP glove, I'm out there every day playing catch with it, it's hot here," Peralta said after the Rays' 5-4 win over the Washington Nationals. "That's what I've got to say about it."
Rays manager Joe Maddon was upset with what happened because of how Peralta was singled out for what Maddon said was "a common practice" among pitchers and for the potential damage to his reputation.
"That Joel does not get vilified, that's my concern, because this guy has done a great job," Maddon said. "He's been an excellent relief pitcher. And to in any way tarnish what he's done to this point because there's going to be suggestions made based on what happened tonight, and I think that's wrong and inappropriate. Because it's been a common practice for many, many years for anybody to try to get an edge in many, many ways."
Peralta used to pitch for the Nationals, and Washington manager Davey Johnson acknowledged he was working with inside information.
"I didn't just make it up or dream it up," Johnson said. "But I mean, there was conversations before the game. He was out there and I was talking to some of the guys and I said, 'How'd we let this guy get away?' I thought he pitched pretty good for us, and I saw he's been a kind of an invaluable setup man for Tampa Bay. One thing led to another, and I got probably more information than I really needed. I don't know."
After Peralta was ejected at the start of the eighth, Jake McGee pitched a scoreless inning. Tampa Bay closer Fernando Rodney tossed a scoreless ninth for his 20th save.