There are two ways to look at Hart. I have never been impressed based on his paper resume, but the more you look into his career, the more you see that he was verry highly regarded for a breif period.
By all accounts Jeffries seemed to hit pretty damn hard, but his finishing ability also appeared to be his greatest flaw. From what I’ve read he seemed to have Fitz and Sharkey hurt at quite a few points in their matches, but either hesitancy or lack of effective finishing skills prevented him from getting those stoppages. Jeffries was seemed way too focused on countering and had too much respect for his opponents to try and finish them like Sullivan or Fitz would.
I suspect that Jeffries coult hit very hard, but had a cautious, 'time will tell in my favor' mentality that, unless he was rile'd (Finegan, Munroe), did not tend to quick stoppages. Jeffries did put away old Jackson and Goddard quickly. Note: I originally flubbed 'old Johnson'; have corrected as 'old Jackson'. Appreciative of McVey's having noticed the error and correcting to 'Jackson' in making his reply.
Jackson was 37, alcoholic ,and consumptive, he also had not fought for 5 and a half years. Goddard was 40 years old. Jackson was tko'd ,Goddard,was rescued by the referee.
There was a historian named Pliny The Mildly More Mature, placing him between other Pliny historians, and he was known to have said Jeffries hit very hard, but that his own comment should be taken into context, as he would not get a chance to see him live for roughly 1900 years after he himself died.
Oh, I noticed I type'd 'Johnson', rather than Jackson. Will correct. You're comments are certainly valid. What I suspect is that, if a fighter was body-vulnerable, they stood a good chance of being quickly retired by Jeffries, without Jeffries especially pressing for a quick stoppage. I suspect Jeffries hit plenty hard, but was not an 'opportunistic' K.O. artist. In a time of 20/25/45/finish encounters, the lack of opportunism wasn't such a demerit, but might have cost Jeffries at some point if he'd come along in later periods.