I kind of figured that May's ex had some powers and had survived. In the episode where they made it seem like he was going to die, the Strucker kid ran away from the scene looking absolutely shaken and terrified. I, also, thought it was strange that May called Colson and told him that he had to save Blair Underwood. That call really seemed to add nothing to the story.
I didn't put together that he was Lash, but after they determined the bald guy wasn't an Inhuman, I figured it out. The key was Daisy wondering why Lash didn't kill her when he had the chance.