DETROIT - Sunday was rookie dress-up day for the Twins, an annual September tradition where the veterans make the rookies board a team flight wearing the most ridiculous costumes they can find.

With 13 rookies on the active roster, it seemed half the team was in costume, and Joe Benson's was especially fitting. He was dressed as a white rabbit in a giant black hat.

To win these days, with such an inexperienced lineup, that's what manager Ron Gardenhire must do: Pull a rabbit out of his hat.

The astonishing free fall continued. Doug Fister pitched the Tigers to a 2-1 victory at Comerica Park, completing another three-game sweep.

At 59-87, the Twins would have owned the American League's worst record if the Orioles (58-87) hadn't blown a late lead in Toronto.

How has it come to this for a Twins team that won 94 games last season?

The Twins are 9-31 since July 30, and while they can't blame inexperience for the beginning of that stretch, the bottom really fell out Aug. 21.

Since that date, they are 4-17 and have been held to zero or one run 12 times. They've started at least three rookie position players in all 21 of those games and haven't had more than five Opening Day starters in the lineup even once.

"It is what it is," Gardenhire said. "People are hurt, they're not playing, and we've got to figure out a way to do it with what we have."

But it seems like the Twins have less and less by the week, and 100 losses have become a real possibility. To avoid that mark, they must finish 4-13.

They've started at least five rookie position players in each of their past six games. After Danny Valencia was scratched because of a sore shoulder Sunday, Joe Mauer was the only Opening Day starter in the lineup.

Chris Parmelee and Benson might be intriguing prospects, but it often looks like the Twins are fielding their minor league All-Star team, with Mauer and others serving as special guests.

"It's never easy on the young players to come up here and make the adjustments," Twins hitting coach Joe Vavra said. "They're facing new pitchers for the first time, and it's their first time in this environment. It's not an excuse. You try to make them feel as comfortable as possible and do what they did that got them here."

After studying the Pitch F/X charts on BrooksBaseball.net, Vavra counted 17 pitches out of the strike zone that Twins hitters chased Sunday. Fister feasted on the Twins' youth, pounding pitches on their hands, as he allowed three hits in seven scoreless innings.

The Tigers have won nine in a row, and are cruising toward a division title with a veteran-laden lineup. On most days, they don't start a single position player with less than two previous years of experience.

The Twins were like that as recently as last year, when a lineup full of veterans churned out victories. Valencia entered the mix as a rookie, and no one asked too much of him, as the machine kept churning.

With the onslaught of injuries this year, these Twins have had to rely heavily on rookies such as Ben Revere, Trevor Plouffe, Luke Hughes and Rene Tosoni.

"In years past, we've gotten the whole lineup to kind of commit to a plan," Vavra said. "It's hard to do that when you've got a ton of players who are trying to survive in each at-bat."

Individually, they're trying to survive. Collectively, they're sinking fast.

Joe Christensen jchristensen@startribune.com