Starcraft 2 Strategy: Watching the GSL Pros

Even the pros can make horrific mistakes.  Some of their mistakes, aside from micro (which can always be improved) are:

• Throwing away too many early game units in the name of "scouting".  
• Losing units by not committing to fights, allowing the opponent to whittle down your army without causing any damage to his.
• Not having a strategy or goal or build
• Sticking with the same unit combination over a long game
• Throwing away units into fixed defenses instead of expanding
• Failing to pull workers away from an attack
• Failing to scout opponent expansions
• Not enough harassment
• Fleeing with units that are going to be run down and killed anyway