Dropped heavily 3 times by Irish Kevin Finnegan, hence footage of those bouts mostly eradicated by Hagler's people to maintain his reputation.
He looked pretty hurt when Leonard invited Hagler to his 'fight with Hagler' party which turned out to be his 'retirement party' when he announced that a bout between him and Marvin will never happen & retired instead.
Did a bit of googling on the Wigfall street fight and ended up with this from the article below which is excellent. http://www.petemyersrules.com/2010/12/tao-of-marvin-hagler.html
Hagler was never significantly hurt in any portion of his filmed career. Hearns' little moment barely registered, and most casual boxing fans would fail to notice it if not for the commentators. He caught a hard shot and dealt with it, and the flurry that chased it, instinctively, coming back stronger in the following seconds. I never saw any indication that Hagler was hurt against Mugabi. He was absorbing punches off The Beast but the extent of the damage was minimal. And you can forget 'the' uppercut; Hagler stepped into a far harder left hook in the sixth round and quite literally walked through it after it jarred his head and carried on with his assault (seconds later Mugabi gave ground and stumbled backwards). Hart's punches had the biggest effect on Hagler; if you really watch the fight, there is perhaps one occasion (just one) in the early middle rounds where Hart seems to rob Hagler of air with a body shot and follows up with renewed interest. Luckily for Hagler it was the end of the round and the bell saved him - not that he was in any danger whatsoever of being stopped, and was only on the borderline of potential trouble. Hagler was seriously tough. I would say he is probably the most unstoppable fighter in history who has sufficient filmed evidence behind him. The Finnegan fights were tough, as was the first Monroe encounter, but I don't recall either being notable for Hagler's jaw giving way. He was staggered by Wigfall, supposedly, but knowing Hagler, it wouldn't surprise me if that event transpired similarly to what happened in the Norberto Cabrera and Juan Roldan fights - a loss of footing being mistaken for genuine damage. Hagler fought some terrific hitters - in terms of sheer force, Hart, Mugabi and Hearns were up there with any in history. Minter, Obelmejias, Roldan, Scypion, Sibson and Briscoe were also good punchers to varying degrees.
I always had it in my mind that Minter momentarily staggered him in their fight after watching it first time round. However having watched it several times since I just don't see it!
Despite being a Hagler fan I agree. That barrage from Robinson on LaMotta in the final fight is just nuts.
Appropriate. When there is a desperate lack of film, it seems fighters' abilities, opposition and legacy are completely blown out of proportion to absurd lengths. If not, they are written off, not taken as seriously and disrespected. Hard to find a median.