Pitcher Dontrelle Willis has reached an agreement in principle on a three-year, $29 million contract extension with the Detroit Tigers, a source told ESPN.com. The deal includes incentives that could push the total value to more than $30 million, the source said. An announcement was expected after Willis took a physical exam Thursday in Detroit. The Tigers acquired Willis and star third baseman Miguel Cabrera from the Florida Marlins in an eight-player trade at the Winter Meetings two weeks ago in Nashville. Willis will join a Detroit rotation that also includes Justin Verlander, Jeremy Bonderman, Nate Robertson and Kenny Rogers.