"Obviously, it's a big blow," Sveum said. "You'd have to make all kinds of adjustments. We'll find out more in the next few days. ... I'm not against anything with 10 games left. Every game is like a playoff game from here on out, so we'll re-evaluate the situation as soon we know more about Benny."
Sheets exited after throwing 24 pitches on Wednesday with what was described as forearm tightness, and later he revealed his elbow injury. He received a cortisone shot at one point over the past two weeks and underwent an MRI, but the ailment was kept secret because Sheets continued to pitch through it.
When Sheets left a Sept. 1 start against the Mets after five scoreless innings, the Brewers said it was because of a tight groin muscle. That was technically true, assistant general manager Gord Ash said Thursday, but the elbow was the real issue. Sveum said he did not know about it until after he was named manager.
The Brewers opted not to send Sheets back to Milwaukee for another visit with head team physician William Raasch. Sheets instead will continue to get treatment from the athletic trainers on site.
"He's seen Dr. Raasch many times and there's nothing [structurally wrong] in there," Ash said. "It's not serious from the point of view that it's career-jeopardizing. There's no structural issues. He's got pain, and he sometimes can pitch with it, and he sometimes can't. Last night was one of those that he couldn't."
Sheets' next scheduled start would be Tuesday against the Pirates. He would then line up to pitch the regular-season finale against the Cubs on Sept. 28.
Ash was encouraged by the fact that Sheets pitched a five-hit shutout against the Padres five days after exiting early against the Mets.
"He'll get his treatment, and we'll literally have to play it day by day to see when he might be available next," said Ash. "We don't know yet."
That's not necessarily the best way to run a starting rotation with 10 games left in the season and the Brewers a half-game behind the Mets in the National League Wild Card standings.
But Ash said the team would treat the injury just like any other. In other words, it would not risk future damage by pushing Sheets into his starts, even though he is a free agent after the season.
"No, you can't," Ash said. "It's the same way with [injured right-hander Yovani] Gallardo. These guys have futures. Our job is to certainly win ballgames, but not at the risk of taking people beyond where they need to be pitched."
Sheets is 13-9 with a 2.98 ERA in 30 starts this season and is three innings shy of his first 200-inning campaign since 2004.