Hendrickson, who last pitched in the majors in 2011 with the Orioles, threw for the team during last week's three-day mini-camp. He threw bullpen sessions on Wednesday and Friday.
In December, the 6-foot-9 Hendrickson began to reinvent himself as a sidearm pitcher. Orioles manager
"It's a work in progress," Showalter said. "He knows it. It's something he's been doing for just a couple months. It's something that's been very intriguing for everybody about presentation. We think it's something nobody's ever seen. I think everybody's a little intrigued to see how it plays. There's no one who is 6-9 who throws from that arm angle."
Both Showalter and Hendrickson both said last week that Hendrickson had already benefited from working with Orioles pitching coach Rick Adair after just the two bullpen sessions.
"Rick understands the mechanics of throwing down there," Showalter said. "And Mark has great learning skills."
Orioles executive vice president Dan Duquette is expected to speak with Hendrickson's agent today.