[fatbird]

You can't judge whether someone was "great" in a particular field if they didn't actually practice in that field. Bargue drawings are very technically demanding, but they're exercises. They don't even count as works of art in themselves.

Just as we can't really say he was a great realist, we can't say he was a mediocre one. He didn't make realist art. We can say that he mastered the skills, so if he'd worked as a realist, he'd probably have been pretty great, if only because once he found a preferable mode of expression, he was actually great.