This is no more cherry picking than what is frequently. done on these boards and in baseball analysis everywhere.
Over the course of a long season, you will often hear a commentary about a team or player start with “Since date XYZ..” or “In his last X games…” When the point is to illustrate a positive trend, the commentator is going to start from a low point, and when it’s a negative trend they will start from a high point.
If you want to reject my comments out of hand because you have a knee jerk reaction to anything I post, I would direct you to Tim Muma’s recent article which breaks down the decline in the Brewers offense in much more detail. He broke down his analysis by starting one day later than I did. I’m not sure why he chose that date, but the trend he is describing is just what I’m talking about. I don’t see you and your friends accusing him of cherry picking.
If you need to know what has fundamentally changed about the Brewers offense, and aren’t swayed by huge drops in production from several every day players, maybe you could consider the loss of the team’s most productive veteran hitter indefinitely, if not for the rest of the season.