I also think that Sherlock has been one step behind Magnusson and he’s failed John by failing Mary. Ever since Mycroft rescued Sherlock he’s been trying to assimilate back into his old life. But his old life is different now. Everyone else moved on. Sherlock is now sort of where John was in the first episode…a bit lost, trying to get a grasp on things and I’d venture to say suffering at least a little bit from PTSD from his time of being tortured and the hyper vigilance he felt was needed to keep his friends safe. John had his limp. Sherlock has his hand tremor.