At times Major League Baseball teams place an underperforming player on the DL (Disabled List). It seems the DL would be meant for players who are injured and or are returning from injury. Why aren't more stringent reviews (evaluations) of player health put in place by the MLB to ensure the player is actually injured prior to placement on the DL?
This happens so much that Grey at razzball even has a term for it. The "Disgraceful List."
The problem with regulating this is that the MLB is very concerned about protecting their players. If the office of the commissioner incorrectly rejected a DL stint for someone that was actually hurt and the Player's Union could prove that there was indeed an injury, there would be hell to pay.
There is no doubt that the disabled list is abused from time to time, but keep in mind that putting a player on the 15-day DL doesn't add an additional spot to the 40 man roster, it only allows for a player on the 40-man roster to be called up to the active 25-man roster. It adds to that player's arbitration/FA clock and uses an option year if they haven't been called up yet. Basically, it benefits both parties, the MLB and the MLBPA to turn a blind eye to players landing on the Disgraceful List.
tl;dr - It's not worth it for the Commissioner's Office to battle the MLBPA over it, especially when some of the "injuries" are things like "arm fatigue" or other conditions that can't be accurately measured by a doctor.