They worked together on the release point in Rondon's delivery, and they worked to get him away from standing straight up. The goal, Jones said, was to get Rondon using his legs more.
The ultimate judge will not come until Friday, when Rondon next pitches in game action. For Jones, the key during Wednesday's session was not how he felt about Rondon's changes, but how Rondon felt.
"He felt good about what he was doing," Jones said.
Rondon has allowed three runs on five hits over 3 2/3 innings with five walks and six strikeouts in four appearances this spring. The bulk of that damage, including all the runs, has come over Rondon's last two outings.
More concerning from a mechanical standpoint has been Rondon's missing up with his fastball. Though Rondon had command issues in previous seasons, his fastball command has been vital. He was largely able to command all of his pitches last season.
Once Rondon gave up two runs to the Braves on Sunday, Jones watched video of Rondon's outings from the end of last season at Triple-A Toledo. Rondon said Monday he immediately noticed something different in his delivery when comparing last season with this spring.
With that in mind, they scratched his game assignment for Wednesday and scheduled the side session.
"Just a little adjustment," manager Jim Leyland said.
While Leyland made a point to emphasize that Rondon was not out of consideration for the closer role, he also said that Rondon had never been named the closer to begin with.
"I think the best way to put it is, I think this kid is potentially a fantastic closing prospect," Leyland said. "Is he ready for that? I can't answer that.
"I don't want to shed any negative light on the Rondon situation, because there is none to be shed. I think this kid has all the equipment. The question is going to become, I think, at some point: Is he ready? Plain and simple. And if he's not ready, the Detroit Tigers will absolutely be fine. I have total confidence in the guys we've got."