CHICAGO -- Padres right-hander Miguel Diaz left his Wednesday start early with a right forearm strain after tossing 2 1/3 scoreless frames in a 3-2 victory over the Cubs.
The extent of Diaz's injury remains unclear, but after the game, team trainers told manager Andy Green that there was no apparent ligament damage. Nonetheless, Diaz will undergo tests and is expected to miss his next start.
"He experienced some tightness, was having some trouble spinning the baseball," Green said. "Every time he did, he could feel it. You never feel good when you hear that, but we don't know how severe this is at this point in time."
Diaz, a Rule 5 Draft pick, exited after walking Cubs center fielder Albert Almora Jr. in the bottom of the third. Shortstop Erick Aybar noticed Diaz attempting to flex his arm in between pitches and called into the Padres dugout. After a meeting behind the mound with manager Andy Green and a team trainer, Diaz was removed from the game.

"I saw him do a couple things that he doesn't usually do, so I ran in there to talk to him," Aybar said through a team interpreter. "He said he was a little bit tight. I was just thinking, with a young guy like that, better to have him out for a start than to have him out for the whole year. That's when I signaled."
Right-hander Craig Stammen entered and promptly got Anthony Rizzo to bounce into a double play. Stammen would later allow a home run to Ian Happ, but that was the only hit the Padres' bullpen would surrender over 6 1/3 scoreless frames.
The Padres acquired Diaz from Milwaukee in December. In 24 appearances for the Padres, Diaz has posted a 6.82 ERA. He moved into the rotation earlier this month and was making his third start.
Of course, the Rule 5 Draft stipulates that a player remain on the big league roster for the duration of the season or be offered back to his original club. In the case of an injury, a player must be active for at least 90 days. Diaz has been active for 79. Regardless of whether it's this season or next, he must be active for 11 more days before the Padres can option him to the Minors.
If Diaz is out for an extended period of time, it's possible he could be activated when rosters expand in September, fulfilling his minimum requirement of 90 days. The Padres hope it doesn't come to that, and Green was quick to note the progress he's made.
"He'll obviously be looked at, get some tests, and we'll find out how long he's out for," Green said. "But he was competing out there against a very good lineup. We're pleased with that, and hopefully he returns quickly."