The fallacy of the predetermined outcome is a type of causal fallacy, derived from counterfactual thinking:
Counterfactuals are conditional propositions, containing an antecedent and a consequence (e.g., If Matt had run, he would have caught the bus.)
where "if only" one item in a sequence of events was different, the outcome would have been different.
While "what if""/"alternate universe" scenarios can make for great stories, not all counterfactual statements are a fallacious. Counterfactual thinking is useful when speculating about possible outcomes (e.g., "if Jeff Gordon hadn't run out of gas, he might have won the race," but becomes a fallacy when a statement is modified to give it 100% certainty (e.g., "if the Pirates had traded for Hunter Pence, they would have won the World Series"). When the antecedent and the consequence also have no direct, logical relationship ("if only Romney had worn different colored socks at the first debate, he would have won the election"), such a fallacy might be better called a non sequitur.
In baseball, the fallacy of the predetermined outcome is commonly associated with Yankees announcer Michael Kay:
Kay often runs into fans who say something akin to: "If only player x had gotten on base, then player y's home run right after x's at bat would have won the game."
Kay counters that we cannot assume player y would have hit the homerun in this hypothetical situation, because we have changed what led up to y's homerun so that all future outcomes are now in doubt - i.e. the playing field is literally changed. … There is simply no way to know for certain what would happen next.
In a broader baseball context, this fallacy is commonly used by people who should know better when comparing the performance of a player after he changed teams in the middle of the season. For example, someone might say, "Trading for Hunter Pence wouldn't have helped my team make the playoffs, he only OPS'd .671 for the Giants". Because of the differences in two teams' schedules, differences in the pitchers faced, differences in stadium dimensions played in, etc., it is impossible to precisely know how a player might have hit if he had been traded to a different team. In this example, one might reply that while there were many reasons why trading for Pence would have been a bad idea, how he hit for the Giants is irrelevant.
So the next time someone cites Brad Lincoln's poor stats with the Blue Jays as exactly how he would have performed if he stayed a Pirate, and expects to be taken seriously, kindly remind said person that their conclusion is not supported by logic.
(Hat tip to JRoth95 for always getting it right)