Of NBC's eight hour-long shows, Timeless is last in viewers (5.55 mil) and 6th in demo (1.33). The only shows worse than it are Blindspot (1.21) and the Blacklist (1.16). Those two shows have tougher timeslots (Wed @ 8 PM, Thu @ 10 PM). Add the factor that Timeless has the Voice as its lead-in, and cancellation is all but guaranteed.
Timeless struggles to integrate its season-long stories with its events-of-the-week. One particular example is that last week's episode, like many of the fillers, did not affect the timeline at all. Therefore, why should casual viewers even watch? Kripke doesn't care about anything beyond showing off (his limited) historical knowledge. He also errs by only making certain episodes
include actual plot progression. How he convinced NBC that making viewers wait for answers and information was a good idea, I'll never know.