From here:
http://seattletimes.nwsource.com/htm..._sonics05.html

it states:
As expected, the Sonics did not pick up the one-year option on contracts for assistant coaches Jack Sikma and Ralph Lewis , which ensures that their contracts will expire June 30. Each signed a two-year deal in 2005 that included a team-option for another year. Sikma may land in Milwaukee, Lewis may be headed to Charlotte, and assistant Gordon Chiesa is reportedly a candidate in Memphis.
Who is Ralph Lewis, you might say? I wondered the same thing, so here it is:
http://www.nba.com/sonics/roster/ralph_lewis.html