No, I choose my words carefully.
You cannot deduce that Losman's work ethic is lacking from a series of observations of him reading defenses poorly. If you were to draw a conclusion from these observations, it would be more induction than deduction. Either way, it's unsound because you do not know the reason for his bad play. Could simply be that he's not talented enough--that he is not skilled enough at processing all the relevant information quickly under fire.
Anyway, to conclude that it's because of a poor work ethic is, like I said, speculation...especially since that was never the word on him. I've never heard a hint of anything from any teammate, coach or journalist that Losman did not work hard.