It's actually not common sense at all. It's an assumption made with nothing to support it. It doesnt' make any sense at all to assume one player will play worse, and have worse stats, because Milton Bradley is on his team. It's a really stupid idea actually, with no support. Gooney is right about one thing, until someone does a specific study directly related to baseball chemistry and productivity, some people won't believe in it, regardless of subjective data/comments from players, coaches or others involved in the game. Of course, their security blanket is the fact that there are too many variables to consider and such a study will likely never occur or be good enough for the one's who disagree. Its a great fall back to have, because he can be fairly certain that you will ever be able to prove without a doubt that team chemistry is a factor. So without a study, you are left between the Gooneys who think it is a "stupid idea" to think one player would play worse because of bad chemistry, or the actual players, coaches, team management and broadcasters/reporters (who actually observe day to day activities and human behavior).