I believe Sharkeys power is underrated since he fought so many top notchers. Much harder to ko top opponents than tomato cans. Most hwts buildvtheir ko record fighting many tomato cans. This is missing to a great extent in Sharkeys resume.
Loughran had a 38 bout winning streak going into the Sharkey fight, but most of that was against light-heavyweights. Starting with the Sharkey fight, fighting heavyweights, he was quite beatable. His record in the 21 fights after the 1st Sharkey fight was 14-7. Schaaf would soon beat him twice. The Loughran fight was a good win but there is no reason to think of Loughran as the best heavyweight out there. There is a point that Sharkey had gone back by the time of the 2nd Loughran fight, but so had Loughran. The two men were the same age, born within two months of each other. Steve Hamas would duplicate Sharkey's feat of knocking out Loughran early. Loughran was a good boxer without a punch and such types have rarely been successful against the very top heavyweights.
What about the bottom line of where Sharkey rates against fighters of his own era. Dempsey? Sharkey was KO'd. He was a peak 25 and Dempsey 32 and going back. Tunney? Off the two men's efforts against Dempsey and Heeney, no reason to see Sharkey in Tunney's class. Schmeling? This one is closer, Sharkey losing early on a foul when ahead of the always slow-starting Schmeling, and then getting the very controversial decision. I can't think of an effort against a common opponent, though, which would favor Sharkey. Sharkey outpointed Stribling, but lost to Risko and drew with Walker. Schmeling knocked out all three. Baer? Sharkey split with Schmeling and Carnera. Baer creamed them. Once Baer started rolling in 1932, he seems to have gone higher, despite being erratic himself, than Sharkey ever did. Louis? He gets into the mix in 1934 & 1935. Obviously, Sharkey is not in his class. Did Sharkey beat all the best contenders? No. By no means. Never fought Uzcudun who KO'd Wills. Never fought Schaaf who beat Stribling and Loughran. Never fought Hamas who KO'd Loughran and beat Schmeling more decisively than Sharkey did. One can overplay his beating top men. He did not fight Tunney, Schaaf, Baer, or Hamas, and lost to Dempsey, Levinsky, and Louis. He couldn't beat Walker, and many of his name victims, such as Schmeling, Carnera, Loughran, Risko, etc. were win one, lose one splits. Bottom line. I see no reason to consider Sharkey the best heavyweight out there at any time, or at least the man who beat the man, even if in a fluky upset, other than what looks on film to be a gift decision over Schmeling.
But when it comes down to it, 13 KO's in 55 fights is an extremely low total. And plenty of other champions fought tough opposition and did better, or at least did better stopping the tough opposition they did fight.
The issue again that in the case of Sharkey his much lower % of tomato can opponents makes his ko percentage less reflective of his power.
Sharkey is of an earlier era than Baer. Jack was a fighter of the 20's into the early 30's. Sharkeys prime was probably the late 20's.
My point with Baer is that he did so much better against Schmeling and Carnera than Sharkey did. Having a really dangerous punch matters a lot in heavyweight boxing. An important point for me is that there is no reason that I can see to argue that either Schmeling or Carnera had gone back since their fights with Sharkey. They fought Baer when at prime age and when they should have been at the top of their form. But Baer beat them much more decisively than Sharkey did. The problem with the Sharkey peak in the late 1920's and early 1930's is that there is no fight which really proves superiority. The guys he beat other guys were beating, plus the draw with Heeney and loss to Risko puts a cloud over even his supposed "prime" dominance. Still, I don't want to be too critical of Sharkey. He didn't draw the color line, unusual for American heavyweights of his or preceding eras. But the heavy downside of losses and mediocre performances can't be ignored either.
If you fight top opposition the chances of a KO win are lower and the chances of losing much higher. Fighting tomato cans usually produces a win by KO thus padding a KO record. Not many can compare with Baer in terms of KO power and no one is comparing Sharkey to Baer in this regard. Sharkey out of 53 fights only fought four bouts against fighters with losing records (three of which were his first three bouts). I believe I read years ago that Sharkey was in the game to make money and to do so he had to fight good opposition. This led him to choose top raters as opponents fight after fight. If you look at his record it's a who's who of contenders bout after bout.
Perry--well let's examine those 13 knockouts 1-----Billy Muldoon (3-7 record) a TC (tomato can) but this was Sharkey's first fight. 2-----Dan Lucas (0-1 record) TC but early fight for Sharkey 3-----Eddie Record (18-10-1) good opponent for early in career. Okay KO. 4-----Mexican Joe Lawson (5-10-1) TC. Setup for a rising contender 5-----Orlando Reverberi (7-4) went 8-7 for career. TC as Sharkey was by this time a rated fighter 6-----Homer Smith (this fight was in 1927 when Sharkey is at top of division. Smith an opponent type who had been losing to the top men for a decade with 15 KO defeats. Journeyman opponent at best.) 7-----Mike McTigue (an ex-light-heavy champ, but smallish at 170 lbs. Sharkey stops him in 12 on a cut. Later that year McTigue was blown out in one round by middle champ Mickey Walker. Fair win, but not outstanding) 8-----Jim Maloney (top KO of highly ranked contender. First impressive display of power) 9-----Jack Delaney (another light-heavy, but this is an impressive KO, although there are rumors that Delaney wasn't really up to fighting because of alcohol abuse. Still, in fairness, let's call this an impressive win, but again over a far smaller man) 10-----Leo Gates (washed up journeyman who was on career ending roll of 12 straight defeats, 8 by KO. TC) 11-----Tommy Loughran (impressive KO, to me by far his most impressive) 12-----Phil Scott (not too durable British heavyweight with the telling nickname of "Fainting Phil" who apparently went down from body punches. Fair win, but nothing to get excited about) 13-----Unknown Winston (like Homer Smith, a journeyman opponent with a 64-51-8 career record and 19 KO defeats.) Bottom line--nothing here to indicate the 13 of 55 performance is not an accurate reflection of a man w/o the real KO power typical of the best heavyweights. Interestingly, the fact that the Maloney and Loughran KO's are on film and commonly available perhaps gives a distorted impression of Sharkey's punching power. And, Sharkey's KO record appears to have its share of tomato cans despite the low total and percentage of knockouts.
It was always strange to me that he had such a low KO percentage. He seems like a good puncher who does pack some power, but it enough. Perhaps it's the combination of an absence of tomato can wins like you said, and also not being a good finisher.
Now here I would have to disagree. I think that after Gene Tunney retires, there is a window where Sharkey is the best heavyweight in the world, even if it was not obvious at the time. I would guess that Schmeling surpassed him somewhere between their two encounters.
I think that there is a much stronger correlation between KO% and quality of opposition, than there is between KO% and power. For example Bob Satterfield had a comparatively low KO%, and nobody questions his power. I never had Sharkey down as a dynamite puncher, but I he was at least a punishing hitter.