This does not affect ESPN+ through Apple TV or Roku. The issue also does not occur on EPSN2, ESPN 3 and ESPNU. Those all have HD 720p streams and also have multiple bitrates. I pulled stream statistics and the best ESPN+ streams give is 894×504 and 2150 KBPS. That is a horrible bitrate and the quality looks poor. This was 2010ish quality.
https://www.reddit.com/r/ESPN/comments/zdh7sa/espn_poor_stream_quality_from_servers_504p_is_the/

