It's obvious in hindsight that Romney never took the election seriously, never made a serious effort to win. He was simply the designated loser.
The video I linked to is only a half hour but it's painful to watch in its entirety. Mitt himself only speaks for 10-15 minutes and he's totally flat and lifeless. Before he is introduced, he's sort of hanging in the backstage area nervously wringing his hands and probably hoping to just get this over with already.
By contrast, Trump absolutely electrifies any room he enters and he truly connects with the audience, usually for 45-75 minutes and still leaves the crowd wishing it was longer.
Totally different election this time around.