What made Canelo fail versus GGG the first time?

I think it's fair to say that Nelo had more tools than GGG going into that fight: -Speed -Timing -Reflexes -Defenses -Youth While GGG only had over Nelo IMO: -Size (lenght) -Stamina Both are accurate, experienced, strong and hard chinned. Yet he failed to beat GGG as the challenger. Some people think Nelo won (most think GGG won) OK but that's not the debate. We can all agree that Nelo had the tools to clearly beat in most people eyez GGG and he didn't. My question is why? IMO I think it was mental and GGG edged it (or made it close) with his will and adjustments. Nelo started naturally outboxing GGG then GGG imposed his will and mental strenght on Nelo. Sometimes it looked like if Nelo could he would have jumped outta the ring. He looked trapped most of the fight and somehow beaten mentally. (the fact that he could have cheated for the rematch, shows that mental edge IMO) Maybe Nelo was surprised by that pressure and will adjust in the rematch, (or "cycled" his but off) BUT, the person I saw really adjusting was GGG IMO, he's the one who won the second half of the fight. If you look at the fight, GGG changed a bit his stance, closed more his guard, and worked with short punches somehow pitty pat combos wich was very effective. But GGG missed most of his big shots and that's on what Nelo mostly focused IMO, not being caught by something big. I think Canelo didn't win because he never made strategic adjusments and let GGG work too much, crumbled under his will/stamina/workrate.