Why did Tunney retire after just two heavyweight title defenses?

I just browsed thru some old newspaper clippings that I have saved on my laptop, & I came across this 1 that very comprehensively sums up the quagmire surrounding Tunney's effort to find a suitable challenger post-Dempsey. It also mentions that Loughran's name was indeed tossed about as a potential candidate for a future title shot.
"Jack Sharkey, the crushed pretender to the throne of Gene Tunney, left this city yesterday accompanied by his manager, Johnny Buckley, returning to Boston a badly disillusioned young man. Johnny Risko, Cleveland's durable crusher of heavyweight championship hopes, departed with Manager Danny Dunn for Cleveland, radiantly happy, as befits a conqueror, and looking forward to bigger and better bouts in the future. But both the conqueror and conquered left in their wake a most complicated and unsatisfactory heavyweight title challenger situation. For their bout at the garden on Monday night each received $24,015. Nobody knows what will happen to the plans of Promoter Tex Rickard for two title bouts this Summer for Tunney-nobody, that is, but Rickard, and he is not saying a word. It is expected, however, that Rickard soon will announce that he has abandoned plans for a title match in the Yankee Stadium on June 14, staging a final elimination instead, and that Tunney will have but one ring engagement, that in September. Who the champion's opponent will be remains to be seen. Speculation was rife on this point yesterday, the eligibles including Jack Dempsey, Risko, Tom Heeney and Tommy Loughran, present light-heavyweight champion, who is prepared to abdicate his 175-pound throne to fight Risko or Heeney or both if Promoter Rickard will guarantee him a meeting with Tunney in the event he comes through successfully.

Rickard to Return South.
Rickard will leave this city tomorrow for Miami to resume his interrupted vacation and discuss the situation with Tunney. Not until the promoter and the champion have reviewed matters from all angles will a definite announcement be made of Rickard's plans. While admitting the outlook is not encouraging, Rickard insists that the situation is not hopeless. As matters stand Risko and Heeney are the survivors of the eliminations that did nothing but eliminate the best ring cards. Delaney, Paulino, Maloney and Sharkey have all fallen by the wayside. Risko and Heeney have waded through the field, but neither stands out as a box-office attraction warranting an expensive ring spectacle. Rickard now plans to match Risko and Heeney as the only solution, hoping for some stroke of good fortune which will establish one of the hardy heavyweights as a suitable challenger. The alternative is to haul Jack Dempsey forth from his retirement and arrange a third meeting between champion and ex-champion. Here, however, Rickard is menaced by the possibility of only lukewarm public interest since it has been pretty well established that Tunney is Dempsey's superior. Furthermore, Dempsey's physical condition is open to question.

Difficulties in Path.
In trying to match Risko and Heeney, however, Rickard is threatened with difficulties. Each wants the Tunney match, though the reason for this demand is hard to explain. Risko thinks that in beating Delaney, Paulina and Sharkey he has qualified for the Tunney match. Charles J. Harvey, manager of Heeney, declares that since Heeney beat Delaney, Maloney and Risko, and fought a draw with Sharkey. there is no valid reason for another Heeney-Risko bout before Heeney fights Tunney. The agreement between Heeney the Madison Square Garden Corporation, binding the New Zealander to fight the Risko-Sharkey bout winner, probably will be enforced. Heeney, according to Matchmaker Jess McMahon, will be given his choice of fulfilling this agreement or being forced to stand on the sidelines. and Any number of attractive matches are available in a revival of heavyweight eliminations and some spirited bidding is anticipated among the promoters. One match contemplated is a clash between Sharkey and Delaney, which Rickard is reported to be seeking as an attraction for Braves Field in Boston. Promoter Humbert Fugazy is seeking a tilt between Sharkey and George Godfrey, current negro menace. Incidentally it was disclosed yesterday that the decision to Risko over Sharkey 'was not unanimous. George Kelly, one of the judges, voted for Sharkey. Stewart Douglas. the other judge. and Referee Billy (Kid) McPartland, however, voted for Risko."

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Rickard's hopes to either arrange a Heeney-Risko eliminator OR lure Dempsey out of retirement were both dashed when the NY Commission stepped in & demanded Tunney name a challenger straightaway or be suspended from boxing in the state.

"NEW YORK, March 27. -(A. P.) Although designed to force an early choice of Gene Tunney's next challenger, the New York State Athletic Commission today delivered an ultimatum to the heavyweight champion and Tex Rickard that apparently scrambles the fistic situation more thoroughly than the promoter's elimination tournaments ever did. The fistic fathers after, solemn deliberation, announced that Tunney must accept the defis of Jack Sharkey, Tom Heeney and Johnny Risko, singly or in toto, by next Thursday, or suffer the equivalent of indefinite suspension in this state. If he does not fancy the "big three" lineup, the titleholder has the further alternative of accepting one or all of the "little four" - Paolino Uzcudun, Jack Delaney, George Godfrey and Phil Scott. In the event that Gene picks from the later division or even names an opponent capable of lifting six ounce gloves into a defensive position, he first must reject the top trio and give reasons. TEX ON WARPATH Instead of accomplishing its conciliatory aim, the commission's action aroused Tex Rickard, in Miami Beach, to bristling response and apparently paved the way for another war of words, the promoter lost no time in rejecting the commisisons'[sic] overtures as untimely and emphasized the contention that it is for him - not Tunney or the commission - to decide the champion's next foe. The commission's move followed Tunney's failure definitely to name an opponent when reuested[sic] by the board at the expiration of the six months' rest allowed a champion between title defenses. The scholar of Greenwich Village merely replied that he had signed with Rickard for a match and the opponent was something for the promoter to worry about. All that kept Tunney from suspension today was the 15-day period allowed for the answer of challenges once they have been filed. Adding to the mounting troubles of Rickard and Tunney, who have been suspected of delaying the game in the hope that Jack Dempsey would make his annual comeback, the commission waived the old Manassa mauler right out of possible consideration. Another Dempsey-Tunney match, they decreed, would be just a "financial proposition," with no possibility of the title changing hands. Although strenuous efforts are under way to bring together Tom Heeney and Johnny Risko, elimination finalists, in a June match to determine a challenger, the bout is being held up by the New Zealander's demand that he receive a written guarantee of a Tunney match in the event he wins. This has not been forthcoming and adds weight to the opinion that Rickard still has hopes of a second Dempsey comeback. The word is out that the only thing wrong with the former champion's eyes is his inability to "see" the figures in the offer Rickard has made him."

 

That's a fair take.
I think it's debatable about Spinks run vs Tunneys but nothing so wide that either side can't make a fair point. Holmes clearly had more in the tank than Dempsey did, going on to have moderate success for years in the division on the flip side Tunney doesn't have a high profile flop like the public execution against Tyson.

Yes Madden was a C level guy but I'm a little impressed Tunney knocked him out quick he was a durable guy and had just gone 12 with post prime Wills.
Risko was pre prime but he was quality and only a year away from his best run of beating Uzcudon, Scott, Sharkey and Godfrey in succession. I think it's a slightly underrated win on Tunney's ledger.

 

Yes I kept it broad and elastic because i didn't care to do an opponent by opponent breakdown. Basically just stating that Gene would be competitive against anyone. To me Tunney looks fantastic in the 5 bouts available of him on film. It's not a huge visual sample but his record backs up that he was an all time top notch operator. I would make him clear favorite over 4 of the 5 lineal champs that succeeded him. Sharkey, Primo, Baer and Braddock. Only Schmeling with his classic right hand I believe could beat Gene. Then onto Louis, Louis could have problems with movers as evidenced by Pastor to an extant and Conn - however Joe has the pedigree and heavyweight punch to finish Gene if he catches him. I see Joe overpowering Gene in the later 3rd of a 15 round fight. tko 11. I think Gene could outbox the slow Marciano. Patterson and Gene would be a fantastic match up. 60/40 Gene. Liston and Ali both beat Gene bout he'd do well and better than guys like Folley and Machen, and could probably duplicate the success of someone like a doug jones against an early Ali.

 

And yet it happened.

 

I struggle to put Usyk in my top ten for the same reasons, whilst not ignoring the fact he is an incredible fighter.