James needs coaching, lots and lots of it - I don't think games like yesterday are fair on him, either. If wanted to go with a 2, he shouldn't have even been a consideration, given the attributes needed to play whilst absolutely surrounded by opposition laser-focused on you and your strike partner.
If you're going to utilise James, you put him out there as wide as possible against as tired a set of opposing legs as possible (impact sub), or, you start him purely with the intention of tiring out his markers or pre-occupying them with his pace.
Putting him in highly technical, pressure-laden positions, that aren't his own, is basically sending him to war without equipment. You can't blame the player for that.
I don't know if he's been 'figured out' or has simply exhausted his very small arsenal. He doesn't have Bale's smarts to utilise kick-and-rush type football, and he doesn't have the technical ability to keep markers guessing, so in that regard, he's basically fecked and he is probably aware and overthinking things because of those limitations. I think it's also pretty apparent the confidence in what he was doing has been absolutely drained out of him, so even within his own sphere of ability, he's not at 100%.
I don't think he'll be at the club in 18 months, because even if he does develop some, he's going to have (potentially) four players, both starters and their rotation partners ahead of him i.e. Sancho/Greenwood on one side (hypothetically) and Rashford/Martial/Chong/New signing or academy product on the other. There's no chance he can usurp the first four under any circumstance except injury/fatigue and the role of 'pace merchant off the bench' is just anachronistic, for all intents and purposes.