Question: Jim Horner has served stints as manager of minor league clubs in which Washington farm team system?
Sentence (from "Jim Horner"): He was previously the pilot of the Class A Wisconsin Timber Rattlers (2006–2007), High Desert Mavericks (2008–2010; 2013) and Class AA Jackson Generals (2014-2015) all Seattle Mariners affiliates.
Relevant evidence: Yes