My take on this fight is to start with you had two great fighters who liked to counterpunch, two counterpunchers can sometimes cancel each other out.
I have also read Hagler was a Duran fan so hence showed him too much respect.
Also Duran was "on" that night which would always spell trouble for his opponent regardless who he was.
As a sidenote according to Leonards autobiography, Leonard was ringside and as the fight finished Duran leant over the ropes and shouted at Leonard something like "Box him, you wil beat him".
When I had the pleasure of speaking to Duran several years ago I asked him what he would have done differently if he had fought Hagler again he told me he would have used more lateral movement and his advantage in handspeed to throw more punches.
What was his English like Joe? You never did send me that pic of you with Manos de Piedre!
There was a time in that fight - my guess is around the 8th or 9th round - when I though Hagler might stop Roberto. Then he backed off and the fight got closer and closer in the scoring. Hagler, one of my favorite fighters of that era, did have his mental lapses. The first fight with Vito, the Duran fight, and of course the Leonard debacle.