Why do teams not trade older players?

There are tons of reasons: -a reward for that player's loyalty -"veteran leadership" - being an experienced role model in the clubhouse -"the human side" - fans have grown to like the player, and wouldn't want to see him go. On the flip side, there are often not a lot of takers for players of advancing age and declining skills. Often, the player was signed to an expensive long-term contract at more than he is currently worth, and it becomes a matter of economics. Also, the receiving club usually wants young players in return, and some clubs are unwilling to give up players who may represent their future for a fading star who may only help them for a couple of months. Typically, it's a lot harder for teams to trade veterans because of contracts. Once a player gets established and gets to sign a new contract, he'll usually be granted some kind of trade protection, such as a full no-trade clause (where he couldn't be traded at all without his consent), or a more limited clause, where he could only be dealt to certain teams. That's not to mention the fact that if a player has played at least ten years in the majors, and the last five with his current team, he automatically has the right to reject any trade. Even if a player wants to be traded, it can still be extremely difficult to do because of his salary. Other teams may covet a veteran player, but they'll seldom want the burdensome contract that comes with him.