Generals, officers and other military men
Strategy: maneuvering as a game of chess
With regard to strategy early eighteenth century campaigns still looked like a game of chess. Due to the technical aspects of warfare at the time it was almost always possible to evade battle when one did not like the conditions. Armies could therefore maneuver for months or even whole campaigns, without any fighting taking place. Generals were thus like chess-players, executing a strategy that tried to pin down the enemy, or tried to avoid getting pinned down.
On the aggressive side this strategy almost always aimed to conquer some cities. It then involved maneuvering in such a way that one would force the enemy either to fight a disadvantegeous battle or to let the aggressor besiege the city. On the defensive one tried to avoid such a situation by maneuvering so that the aggressive side could only besiege the city by fighting a disadvantegeous battle.
All this meant that open battles were seldom fought, but that the strategic skills of a general were very important. Some examples: During the march to Peer Marlborough maneuvered in such a way that Boufflers was forced to retreat from the Colognese, Boufflers could have fought him, but not at favorable conditions. The allied maneuvers which led to the Cannonade at Helchteren were meant to prevent the French from disturbing the siege of Venlo. Marlborough offered battle at Helchteren, but on conditions that were disadvantegeous to the French. The 1707 campaign in Flanders saw two able strategists not able to force each others hand. With regard to strategic skills one can state that good generals were those who got advantages and were never forced to fight a battle they did not like.
Command: Directing a battle
All the above meant that when a battle was fought the sides were often about evenly matched, or at least thought themselves to be so. If both sides did not make mistakes such an affair was generally very bloody, but not very decisive, yielding the victor a city or fortress. With regard to fighting battles one can say that a good general was someone who stayed in control, did not make mistakes and knew how to profit from the enemy's.
Some of the battles fought during the War of the Spanish Succession were so decisive that one can question the competency of the generals as commanders. Competency could be scaled as: great, competent or incompetent.
Compency of generals: logistics, command and control and reconnaisance.
Being a competent general would mean not making serious mistakes in the 'chess game' nor while commanding a battle. This again boils down to having an eye for logistics, command and control and reconnaisance.
Great would mean that a competent general knew how to profit from the enemy's mistakes, outmanoeuvring him or inflicting slaugther on the battlefield. An incompetent general would be someone who made mistakes in manoeuvring, gets surprised and/or loses control of a battle.
Judgement is of course difficult, especially because sources tend to be coloured, but also because the strength of troops on the field cannot be judged only by training, weaponry and numbers.