"Any Outdoor Professional League Team that is majority owned by a higher-level Outdoor Professional League Team shall be ineligible to participate in the Open Cup. The Open Cup Committee shall review and determine team eligibility annually pursuant to this provision and report its decisions to the National Board of Directors."
The amendment to the bylaw was approved on September 8th, 2015 by the USSF board of directors.
The change eliminates the Seattle Sounders 2, Portland Timbers 2, LA Galaxy 2, New York Red Bulls 2, Real Monarchs (RSL) and 2016 expansion teams Orlando City B, Bethlehem Steel and Swope Park Rangers (Sporting KC).
The change was likely due to some MLS teams manipulating rosters to save reserves for higher levels, and purposely fielding weaker teams. The NY Red Bulls 2 for instance fielded an Open Cup team comprised mainly of U19 and U16 players from their academy. This change should eliminate the need for roster manipulation, and roster a bit of competitive balance.
This change does not affect the Colorado Springs Switchbacks FC, who are independently owned, nor the Colorado Rapids affiliated team, Charlotte Independence.