This is one time where the standard interpretation holds fairly true: Washington was excellent at devising a system that allowed the United States to win the war and holding the army together long enough to not lose it, but he was no Napoleon or Alexander when it came to maneuvering units on the field. Washington was best when planning a battle: setting up defensive lines for soldiers to retreat to (Long Island), or determining to attack at unexpected times and places (Trenton, Princeton, Yorktown). He fought decently at Brandywine and Monmouth, and poorly at Germantown.

Sources: Martin and Lender, A Respectable Army

Lender and Wheeler, Fatal Sunday

David Hackett Fisher, Washington's Crossing