Chamberlain turned out to be an excellent regimental commander and a very good brigade commander. John Gordon was an outstanding regimental and brigade commander and a very good division commander. He also briefly served as corps commander but that was at the end when it didn't mean a whole lot and it would have been interesting to hypothesize what kind of corps commander he would have been earlier in the war.Would you mind elaborating on that? I'm only relatively familiar with Chamberlain's record and even less with Gordon's. Guess I need to do a bio on him to learn more.
Anyway, re Barlow: If it's because of Gettysburg, at Barlow's Knoll, I agree; he went too far forward and found himself unsupported. But he could only work with what he had in troops. To rephrase Pickett: The Confederates had something to do with that too.
Barlow was a very good regimental commander, was very briefly a brigade commander, and didn't do all that well at Gettysburg. In addition, on at least two occasions during the Overland Campaign, he also isolated himself from the rest of the corps and was very nearly overwhelmed. He had a tendency to get himself into situations that he couldn't get himself out of that could very well have been disastrous. I don't recall the exact dates of these two events but will try to look them up when I get a chance.