There's no hesitation or holding back in Jim's movement trying to counter Isidor. Ducking and dropping back half a step to his right before putting all of his weight forward into his own strike, Jim moves with a dogged pace. Not bothering to fall back properly.

Frankly, the captain knows already that if he doesn't try his hardest it's only going to take one or two blows to knock him flat on his ass. Which might happen anyway as Jim's full momentum is easily countered and used against him by Isidor.