So why have the Brewers' successes and shortcomings over the past few seasons been so closely tied to No. 15? Sheets is set to make his sixth Opening Day start in the last seven seasons on Monday when the Brewers play the rival Chicago Cubs at Wrigley Field, and he's been a bellwether for a franchise that has been unable to make the postseason in each of the last 25 seasons.
In 2006, when the Brewers lost Sheets and Tomo Ohka to shoulder injuries, the replacement starters went 6-17. Last year, the Brewers were 13 games under .500 during the time that Sheets missed with finger and hamstring injuries. Those 13 games loomed large when the Brewers finished two games behind the Cubs in the National League Central.
Unfortunately, the injury-shortened year extended a trend. Since Sheets made 34 starts and pitched at least 200 innings three straight years from 2002-2004, he has not made more than 24 starts or pitched more than 156 2/3 innings because of a variety of ailments that, apologies to Yost, have been more serious than "little nagging injuries."
"I don't feel sorry for myself one bit," said Sheets, who turns 30 in July. "It's the hand you're dealt with. Nobody wants to get hurt."
Everyone seems to have their theory about why Sheets has been snake-bitten. Most revolve around questions about his conditioning, but Yost blows them off because they come from outside the clubhouse, "from people who don't know."
Pitching coach Mike Maddux points to his brother, Greg, who will never be accused of spending too much time in the weight room. Pitchers tend to stick with the regimen that made then successful, and Sheets' success from 2002-2004 was as good a blueprint as any, Mike Maddux said.
"There's only one way to get in shape to pitch, and that's to pitch," Maddux said. "You can go ride the bike all day and that doesn't equal innings. Take a look at him right now. He's in as good of shape as I've seen."
Still, Sheets' mostly "weird" injuries have taken their toll. First, it was a rare inner-ear ailment in 2004. Then, a torn "lat" muscle in Sheets' upper back -- the Brewers still can't find evidence of another pitcher suffering that one. Then, he missed six weeks last season when he tore tissue surrounding a tendon in his right middle finger.
"I was happy when he pulled a hammy," Maddux said, referring to the injury that sidelined Sheets over the final week of 2007, just as the team was fighting the Cubs for the division. "At least that was a baseball injury. The other stuff is, 'why me?'
"Here's a dude that threw 200-plus innings for [three] years in a row, and you set your bar at that," Maddux said. "Your minimum is 200. He could have gone out and gave us more innings last year, but they wouldn't have been worth a darn. You're not going to go out there just to go out there. You want to perform."
If Sheets performs this year, he will be richly rewarded. He's entering the final season of a four-year, $38.5 million contract that was the largest in franchise history when he signed it.
The Brewers have decided to wait until the end of the season to decide whether to offer Sheets another contract. For his part, Sheets said he will not take his contractual issues to the mound.
"To me, that's business and that's totally different than baseball," Sheets said. "I've never worried about it, and I'm not going to worry about it. That has no bearing on how I play the game. I can honestly say that's never crossed my mind when I'm on the field, or even during the season. There's plenty of time between seasons for all of that to happen.
"When you look back at the end of the year, you are who you are. Your numbers are what they are. That's all it is."
He'll start compiling those numbers on Monday.