A finish like James' tells me that he went slower in the first 200 than he could have. I think this was a really fast day for him where he could have gone well below 44 had he had a slightly different race model.
As to his form, he has definitely gotten stronger IMHO. He still runs a bit like a duck, but a bit of turnout in the feet can actually enable longer strides if done correctly, which is a great thing in the 400.
His arm swing in this final 100 was terrific, and his torso position looked advantageous. That guy was moving, he was literally running away from Merritt.
Right, Merritt didn't fade badly at all--but today was no contest. I thought James looked invincible. I don't think he'll necessarily get 43.18 as some are predicting, that's a really great time--but he will be among the all-time 400m greats when he is done.