I have found that when I try to take "hands off" the Dutch, when running my First Anglo-Dutch Wars scenarios, the English will start to win. As soon as I start maneuvering the Dutch as a fleet, the Dutch will improve. If their losses and damage are not too great, they will even start to win. The only concern is to not waste ships trying to kill English 1st and 2nd Rates that are dismasted or otherwise heavily damaged. The only way to kill them is to rake them from both ends, mercilessly, and stay out of their field of fire. Doing so is only practical in a "fight to the last ship" (if that can be said to be practical).