The structure in The Imitation Game was very problematic. Weaving in and out of three stories spread over forty years is always going to emotionally distance the audience from the characters. The story of Turing falling in love as a young boy offered the main pathos of the movie and was the filmmakers' attempt to make us forgive Turing for his ill-treatment of others as an adult. But it didn't add much if anything to the main story of breaking Enigma, nor really even of explaining his social disorders. Just because somebody has their heart broken when they are twelve does't excuse that person treating all other people badly forever. What was gained from the boyhood story could have gotten done in one short scene, we didn't need to spend twenty minutes of the movie going back there.
Flashing ahead to the investigation of Turing by the police also added little to the main story. The whole episiode was contrived to get to the historical fact that Turing was prosecuted for indecency. It would have had more power to the audience it if had been left as a title card at the very end. What was lost in audience engagement by the periodic flashing forward to watch the police figure out something the audience already knew, ended up as an insurmountable obstacle to the storytelling.
Every time The Imitation Game jolted back into the distant past or ahead into the future the audience was lifted out of the movie and distanced from the illusion of the story as being their story. Flashbacks and flash forwards are very, very tricky. They belong on the shelf of tools on the cinematic workshop which has the sign, "Just because we can doesn't mean we should."