"He's fine, I think he's going to be very usable," Leyland said. "But you might as well make up your mind, you're going to have some growing pains, that's just the way it is. To expect him to come up here and wipe out the big leagues night after night, that's not going to happen. But he has a lot of ways to help our ballclub, and I think he will."
According to the data and statistical website Brooks Baseball, Rondon is throwing an average of four sliders in each appearance since his return to the Majors, and Beckham's home run was the first hit against his slider.
"He's a weapon," Leyland said. "I was glad to see him throw some sliders, because it makes the fastball better, and when it's a fastball like that, it's a lot better. Like I said, he's not a finished product, but he'll be fine."
Said Rondon: "I've adjusted to my pitches and I trust my breaking ball more."
Pitching coach Jeff Jones has helped Rondon make small adjustments with his arm action so it's harder to pick up his 101-mph fastball.
"There's a reason some guys throw 95 and throw it by people, and other guys throw 95 and they whack it," Leyland said. "Most of the time it's either straight as a string, it's in the middle of the plate, or they pick it up real quick. In his case, he's kind of in between. He's probably got to do a better job, but he's hiding it a little better."
Jason Beck is a reporter for MLB.com. Read Beck's Blog and follow him on Twitter @beckjason. Bobby Nightengale is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.