Since its the off-season, and we haven't traded for Mike Stanton yet, here's a little primer on the root definition of evidence.
Evidence is relevant if: (a) it has any tendency to make a fact more or less probable than it would be without the evidence; and (b) the fact is of consequence in determining the action. Federal Rule of Evidence 401.
Imagine that this wall is a proved theory. The bricks making it are proved evidence. For example, if you wanted to prove that A-Rod took a morning walk in the snow, evidence for that would be:
1. That it snowed at his house,
2. That tracks led from his house,
3. That the snow was fresh,
4. That the tracks belonged to a large man,
5. That A-Rod is the only large man who lives at his house,
6. That an eyewitness saw him away from his house on the morning in question, with gloves and a hat on,
7. That the eyewitness did not see him with any visible means of transportation.
8. That A-Rod appeared to be walking.
The amount of evidence needed to prove the theory, that A-Rod took a walk on the morning in question, is called a burden of proof. American Law generally has five burdens of proof, 1. A reasonable suspicion, reserved for when a policeman may temporarily detain someone to investigate a crime, 2. A probable cause, which is the standard allowable for making arrest or for a search warrant to be granted. There is a probable cause when a set of facts, ignoring any set of contrary facts, makes an event more likely than not 3. A preponderance of the evidence, or more likely than not, which is generally reserved for civil issues involving a deprivation of property. A preponderance of the evidence differs from a probable cause in that it takes facts contrary to the theory into account, and weighs them, rather than ignoring them.
4. clear and convincing evidence, which is generally reserved for deprivations of a fundamental right, such as a termination of parental rights, and 5. Beyond a reasonable doubt, which is generally reserved for deprivations of life or liberty. Beyond a reasonable doubt generally means that there is no contrary fact or lack of evidence for the theory that would make a juror hesitate to believe that the theory was true, even if the juror's own life, liberty or property rested on the theory.
If you wanted to prove that A-Rod took a walk by a reasonable suspicion, then you could show that there were tracks coming from his house. If you wanted to prove that A-Rod took a walk by a probable cause, you could show that there was fresh snow, and that tracks from a large man led from A-Rod's house. This probable cause would exist even if you knew that Jeter and other friends had also stayed the night at A-Rod's after A-Rod's party.
If you wanted to prove that A-Rod took a walk by a preponderance of evidence, you should be able to prove so by facts 1-4, that it snowed the night before the alleged walk, and that large man tracks led from A-Rod's house, and that there was no contrary evidence negating it.
The higher standards of proof would probably require that you proved that the large tracks did not belong to some overnight house guest of A-Rod's.
There are some problems with applying burdens of proof to baseball theories.
1. No one agrees what the applicable burden of proof for baseball is. Do we need to prove everything by beyond a reasonable doubt? Wouldn't that leave out lots of interesting articles? The most entertaining baseball theories are often the most farfetched. If you wrote "Erasmo has turned to Sid Finch" that would be worth a read, but if articles were limited to what is absolutely provable, the it would limit discussion to boring consensus baseball theory. It is proved beyond a reasonable doubt that Ground into Double Plays kill rallies, and it is proved beyond all doubt that home runs put points on the board. But if you require a high standard of proof, it doesn't leave room for enough topics to operate a baseball blog.
2. Even if there was a standard burden of proof, who gets to decide whether it has been met? Who is allowed to jure baseball theory in the court of baseball?
3. Opinions vary wildly on the quality of baseball evidence. Some stats are scofffed at as being unreliable, for example UZR, while other eyewitness accounts are scoffed at as unreliable for being a "small sample size". If you were going to judge a baseball theory, it would be best to receive judgment from a jury panel from media, ex ballplayers, fans, scouts, and stats guys, rather than from an individual judge who favored one of those viewpoints.
4. Judging baseball theories at all shows that maybe the sport is taken a little bit too seriously. Baseball should be fun. If it causes anger, maybe it is time for a new hobby.