Brad Radke has retired, Johan Santana is long gone and Francisco Liriano's career continues to tease.

Those who believe the Twins need a true ace won't find one on their expanded September roster or knocking on the door in the minors.

Kyle Gibson will undergo Tommy John surgery Wednesday. The best candidates to bolster next year's rotation are getting chances this week.

Anthony Swarzak pitched Game 1 of Monday's doubleheader against the White Sox, and Scott Diamond pitched Game 2, as the Twins got swept 2-1 and 4-0 at Target Field to fall to last place in the AL Central.

On Tuesday, the Twins will introduce their next best hope: Liam Hendriks, a 22-year-old righthander from Perth, Australia.

Hendriks does not have overpowering stuff, but he's the favorite to win the Twins Minor League Pitcher of the Year award. Past winners include Scott Baker (2004), Liriano (2005), Matt Garza (2006), Kevin Slowey (2007) and Gibson (2010).

Hendriks went 8-2 with a 2.70 ERA at Class AA New Britain and then 4-4 with a 4.56 ERA at Class AAA Rochester before getting promoted Sunday, racking up 111 strikeouts and only 21 walks in 139 1/3 innings between the two stops.

"He's a guy that locates the ball," manager Ron Gardenhire said of Hendriks. "His fastball's 88-89 miles per hour. He's pretty consistent, but if he starts trying to throw it 91-92, he'll be in trouble. He's gotta stay with what got him here."

This is true of most Twins pitching prospects. Overpowering pitchers are hard to find, especially when you're constantly picking low in the draft.

That's one positive that will emerge from this train wreck of a season. At the rate they're going, the Twins could have a top-five pick in next June's draft. Maybe this will help them land a dominant top-of-the-rotation starter.

Even when healthy, Gibson isn't overpowering. He has been compared to Scott Baker, with slightly better stuff. People who saw Gibson and Hendriks this year at Rochester were more impressed with Hendriks, though at 6-1 he is five inches shorter than the 6-6 Gibson.

"He's not a big guy; he's a little guy," Gardenhire said. "He relies on location and sink, and us catching the ball behind him. We'll see how it goes."

Gardenhire knows his team's infield defense is suspect. This is an area the Twins must upgrade, significantly, if they're going to keep churning out pitch-to-contact specialists. But that's a story for another day. For now, the Twins just look forward to watching Hendriks compete.

Twins infielder Luke Hughes, another Perth native, has played winter ball with Hendriks for years. In 2009, they were teammates for Australia in the World Baseball Classic.

"[Hendriks] was 18 years old, but the bright lights didn't bother him," Hughes said. "He's a competitor. He has that kind of edge you look for."

Hendriks had all his stuff packed for a seven-hour trip with Rochester this weekend, when Red Wings manager Tom Nieto pulled him off the bus and told him he had been promoted.

Hendriks' said his girlfriend will be at Target Field watching Tuesday. His parents visited earlier this summer, and with short notice, there wasn't time to return for his major league debut.

"It's understandable," Hendriks said. "But hopefully I'm here for the month, and I can get them back here."

The Twins haven't said what they plan to do with him after Tuesday's spot start, which was necessitated by Monday's doubleheader. But if he fares well, they will find spots for him. This team needs all the bright spots it can get.

Joe Christensen • jchristensen@startribune.com