"Opinion: a view or judgment formed about something, not necessarily based on fact or knowledge." This is true.
"An opinion, by definition, can't be wrong; it is based on a viewpoint. It is how someone views something. A viewpoint can't be proven or disproven; it is an opinion." I don't think this follows logically.
In this case @rwilfong86stated that the team quit on Baldelli. A serious accusation against the players and manager. In a bad season the team's best stretch of ball was the last three months. If a team had truly quit how would that manifest itself logically? By playing better? Sometimes things have to make sense, don't they?