BALTIMORE — Johan Santana threw a pain- and problem-free bullpen session here this afternoon at Camden Yards that pitching coach Dan Warthen called “vintage Johan.” Santana is under the microscope, obviously, after posting a 6.50 ERA in his past six starts and giving up a career-high nine runs in his previous outing Sunday at Yankee Stadium.

Warthen said Santana changed his grip during the 47-pitch outing and, more importantly, lowered his arm angle after letting it get a little out of whack.

“I thought he was excellent – vintage Johan,” Warthen said. “I think we have most everything figured out. He got his deception back and his velocity back, and I’m expecting very good things [in Santana’s next start].”

Santana takes the mound again Saturday at Citi Field in an interleague game with the defending AL champion Rays.