Complex sentence: He was their head coach for them until he became head coach of the first team in December 1998 Then Adrion was head coach of VfB Stuttgart from December 1998 to May 1999.
Split into simpler sentences: He was their head coach for them until he became head coach of the first team in December 1998. The third stint happened from June 2004 Then Adrion was head coach of VfB Stuttgart from December 1998 to May 1999.