Why didn't you just tell him what you knew? Seems like he was looking for your feedback. Or I might have asked him "which guy? Which bayonet charge?" lol...
Oates and his men were definitely powerful enough to actually smash through that flank, and vastly outnumbered Chamberlain. But Oates didn't know that. For his part, Chamberlain's success in stopping an important flanking move by a very tough opponent was a seemingly unlikely victory. He obviously didn't win the entire war,(wow! not even close!)or even the entire battle. But let's be clear: that flank was definitely going to collapse, and if you don't think the 15th Alabama would have exploited that in concert with the 47th AL, and the 4th and 5th TX, you probably don't respect the prowess with which they fought. Especially Oates and the 15th Alabama. His reputation was well earned IMO, but I think the 14 men of Berdan's 2nd US Sharpshooters who harrassed Oates ever since the Slyder farm continued to have an impact on their perception of the size of the force they were dealing with.
(Edit: And I think based upon recognition of impending collapse, and upon taking the initiative, Chamberlain's reputation was well deserved and had a very large impact on the outcome of a battle that is thought to have "turned the tide" for the Union. I respect him greatly for it, personally)